Questions are related to the Everyday Science Short Questions with answers which are very important to pass the entry tests of cadet colleges.
These questions are very useful to understand the basic concepts of Everyday Science. For more preparation of Everyday Science, see the following links;
Everyday Science Short Questions & Answers (Part-1)
Q. Define radiation and explain how heat is transferred by radiation?
- The transfer of heat energy from a hot body to the cold body directly, without heating the space between the two bodies, is called radiation.
The heat from the sun reaches us by radiation. Air is a bad conductor, so conduction and convection can never reach us. In convection, hot air rises to leave the space for colder air, so convection and conduction are sources not used for the sun’s heat to reach the earth. So the only source of heat from the sun or any other heater to travel is radiation never requires a medium.
What are good and bad radiators and absorbers of heat?
- Black surfaces are sound absorbers and suitable radiators of heat.
- Shiny surfaces are bad absorbers and bad radiators of heat.
What is the application of radiation of heat?
Everyday application of radiation of heat:
- Every object emits or radiates some amount of heat. Knowledge of radiation can help us in many ways.
Warming body in water:
- When we sit beside a fire, the heat of fire reaches us through radiation. It does not warm the air between us and fire.
Cooling in a cooling machine:
- The cooling fans at the back of our refrigerators need to radiate quickly to the surroundings. Its surface is made rough and painted black.
Wear light colours in summer:
- It is advised to wear white or light-coloured clothes during hot summer days. White colours absorb less heat than dark colours.
Use of greenhouse:
- In cold areas, a greenhouse is used for the better growth of plants. Radiation from the sun passes through the glass or plastic and warms up the soil and plants. Plants and soil absorb and emit radiation and increase the temperature in the greenhouse. Plants grow well in the increased temperature of the greenhouse.
What is a vacuum flask? How does it work?
- A container keeps the hot things hot and cold cold-called a vacuum flask.
Structure of vacuum flask:
- A vacuum flask consists of two thin glasses or metal bottles, one inside and the other outside. The air between the glass walls is removed to create a vacuum. The walls of the bottles are coated with aluminum on the vacuum side. The surface acts as a mirror, and smooth glass walls prevent heat transfer by radiation. The mouth of the flask is made from a bad conductor such as cork or plastic. A very little amount of heat is lost by conduction through the mouth. Thin-walled glass is protected by keeping it in a metal or plastic container.
Metals are a good conductor of heat; why?
- Particles of metal are closely packed, so one particle collides easily with the other to transfer heat. They also have free electrons to speed up the transformation of heat.
Define and explain refraction?
- Light does not need a material to travel. Light travels faster through the vacuum. It travels at different speeds through different mediums.
- Lighteners from one transparent medium to another change speed and direction. This change of direction or bonding of the ray is called refraction.
- When light falls perpendicular to the surface of the medium, it does not change its direction.
In what direction does a ray bends while light passes from different mediums?
Light ray bend when it enters from one medium to the other:
When light ray enters from air to water:
- When light passes from air to water or glass, it bends towards the normal (perpendicular). The angle of incidence is greater than the angle of <refraction.
When light ray enters from glass to air:
- When light passes from water or glass to the air, it bends away from the normal. The angle of reflection is greater than the angle of incidence.
Everyday Science Short Questions & Answers (Part-2)
Discuss the effects of refraction?
Effects of refraction:
- Whenever we open our eyes, we observe the refraction of light.
- The lens in our eye refracts light to form an image on the retina of our eye.
- As shown in the figure, a pencil in a glass of water looks as if it has been broken at the waterline. It is because of the refraction of light.
- Refraction causes the formation of the rainbow.
- Refraction occurs in lenses used in spectacles, telescopes, and magnifying glasses. Etc.
Define the following terms. Incident rays, refracted rays, normal angle of incidence, angle of refraction.
- The ray of light that falls on the surface of the other medium.
- The ray of light changes its direction in the other medium.
- An imaginary line is drawn perpendicularly on the surface of the medium at the point where the incident ray falls(point of incidence).
The angle of incidence:
- The angle between the normal and the incident ray. It is denoted by
The angle of refraction:
- The angle between the normal and the refracted ray. It is denoted by <r.
Define the refractive index, and write its formula.
- The speed of light varies in different mediums. Some mediums cause light to bend more than others when it passes through them.
- “The degree to which a medium can bend light is given by its refractive index, “for example, and right bends in water. The Refractive index is the ratio of the speed of light in a vacuum to its speed in the medium.
Why the real and apparent depths are different?
Real and apparent depths:
- Sometimes refraction of light gives us a false impression of the depth and position of objects in water or glass. E.g., we have noticed that clear swimming pools look shallower than their actual depth. It is because of the refraction of light.
- Light travels faster in the air than in water. When light passes from a denser medium (water) to a rarer medium (air), it bends away from the normal. When this refracted light enters our eyes, the bottom of the pool and objects lying on the bottom appear close to us than they are.
Define critical angle.
- If the angle of incidence is gradually increased, a stage will come when maximum refraction occurs, and the angle of refraction becomes 90°. This stage of incidence is called the critical angle.
- It is denoted by <C°. The critical angle for about 49°, while for glass is 42°.
Write down the laws of refraction and give its equation.
Laws of refraction:
- The incident ray, the refracted ray, and the normal all lie in the same plane.
- For two particular mediums, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
Define total internal reflection.
Total internal reflection:
- When the angle of incidence(1) is greater than the critical angle “c,” the light rays reflect in the same denser medium. This phenomenon is called total internal reflection.
Total internal reflection takes place only when:
- light passes from a denser medium (water or glass) to a rarer medium (air).
- The angle of incidence of all rays must be greater than the critical angle of that denser medium.
What is the application of total internal reflection?
Application of total internal reflection:
- Many optical instruments use the principle of total internal reflection for their working, e.g., prism, binocular, periscope, mirage, fish eye view.
What is a prism?
- A prism is a glass block with three rectangular and two triangular surfaces. A right-angled prism has one 90° and two 45° angles. The critical angle for glass is about 42°. When light enters the prism, it will be internally reflected.
Which prism and principle are used to make binoculars?
- The critical angle for glass is around 42°. When light enters a right-angled prism, it makes an angle greater than the critical angle. It causes total internal reflection to take place. Binoculars use reflection prisms to see distant objects.
Explain the structure of the periscope.
- A simple periscope consists of a tube, at the ends of which are fitted two right-angled prisms. The first prism turn light was coming from the object toward the second. The second prism turned it to our eye.
Principle of periscope:
- The prism uses the principle of total internal reflections.
- Periscopes are used in submarines, tanks, etc.
Everyday Science Short Questions & Answers (Part-3)
What are mirages. How are they formed?
- A mirage is an image of some distant objects that appears to us due to the light’s refraction and total internal reflection. Mirage is seen on the road ahead where water seems to be there, but water is not there.
How mirage formed:
- The air higher up is cooler than the air near the surface, which is not. The light moves faster through the hot air. When light enters from colder gas to warmer gas, it shows refraction.
- Near the ground, the air is much warmer than the light rays begin to travel almost parallel to the ground but continue to bend in other directions. So, total internal reflection takes place. When we see their bending light rays then, Our brain assumes that the rays seem to us as reflecting from the water. As a result, a mirage is observed. Mirages are mostly observed in deserts.
Explain fish eye view?
- When light travels from one medium to another, its speed changes, this speed change causes it to reflect and refract at the boundary.
- When light travels from water to air, it bends away from normal due to its speed change. When the angle of incidence <i is greater than 48° degree, all the light reflected into the water, e.g., the internal reflection, will occur. When the fish looks up, it will see a reflected view.
Describe the spectrum and how it is formed?
- Sunlight is composed of seven colors, but it is appeared white. Those colors are red, orange, yellow, green, blue, indigo, and violet.
Dispersion of light:
- The splitting of white light into its component colors is called dispersion of light.
Why does the white light get dispersed?
- White light is composed of seven colors. Each color has a different speed in the same medium. So when they enter from one medium to another medium, their speed also changes differently. Hence their bending will also be different.
- When light enters a prism, all the colors are refracted at different angles. Red light bends least, and violet light bends the most and refracts by the longest angle. In this way, white light disperses into its components’ colors.
What is a rainbow, and how is it formed?
- It is a natural demonstration of refraction, dispersion, and total internal light. A rainbow may appear when the sun shines through tiny raindrops suspended in the air after the rain. These raindrops in the air act like tiny prisms. They reflect and refract the sunlight into different colors, exactly like the spectrum of white light given by a prism. Since red colors bend the least and violet bends, colors bend the most from the original path. So red color appears at the top and violet at the bottom of the rainbow. Another colure appears in-between as given in the series. Violet- indigo- blue- green- yellow-orange-red.
What are the primary colors? How are deterrent colors produced?
- The colors that can be used to make any other colors are called primary colors. They are red, blue and green. When these colors are mixed, they form white light.
- Any two primary colors are mixed equally to produce secondary colors. These are cyan, yellow, and magenta.
Red +Green =Yellow
Red +Blue =Cyan
Blue +Green =Magenta
- Many other colors can be obtained by mixing primary and secondary colors.
How the colors of the object are formed?
- Non-luminous objects reflect some colors of the white light, and colors are absorbed. The color of the object is the color of the light it reflects.
- The red color objects absorb all other colors of white light, and red is reflected, e.g., red rose.
- The grass is of green color as it reflects green, and the other six colors are absorbed.
- The blue color appears as if all other colors are absorbed by the object but not the blue color.
- When no one color is absorbed by the object and all other colors are reflected in our eyes. The object would be of white colors.
- When the object absorbs all the colors, that appears black.
- All other colors are formed by the mixing of primary and secondary colors.
- A wave is a disturbance that transfers energy from one point to the other. Wave can be produced in liquid gases and solids.
What is meant by medium?
- Many waves require some material to travel through. This material thing is called a medium. Gases (air), liquids(water), and solids (rope or metal) all act as a medium.
Explain how the waves are produced?
Waves in spring:
- Hold one end of the rope and move it up and down. You will produce waves in it.
Waves on water:
- We can also create waves in water by dipping our fingers repeatedly in water. We see that vibrating movements can create waves.
- A vibration is repeated to and fro or up and down motion.
Everyday Science Short Questions & Answers (Part-4)
What are the types of waves?
- A wave in which particles of the medium move perpendicularly to the path of the waves is called a transverse wave. Waves that are produced in water are transverse. Transverse waves are also produced by the up and down movement of the rope.
- The highest point of a transverse wave is called a crest.
- The lowest point between two crests is called a trough.
Define longitudinal waves.
- A wave in which particles of the medium move back and forth parallel to the path of the waves is called a longitudinal wave. If we stretch out the spring and pull its one end, we can produce a longitudinal wave.
- The parts of a longitudinal wave where particles of the medium are compressed together are called compression.
- The parts of a longitudinal wave where particles of the medium are spread out are called refractions. As the wave moves, compression and refractions are produced due to the back and forth motion of particles of the medium. Sound from a vibrating body produces longitudinal waves in the air. These waves reach our ears and affect the eardrum.
- Compression and rarefaction are combined to form a longitudinal wave.
Explain how the sound waves are longitudinal?
- A sound wave traveling through air is an example of a longitudinal wave. When the drummer beats a drum then, the surface of the drum vibrates. It creates a disturbance in the air besides.
- When the drum head moves to the left, it compresses the air particles and creates a compression.
- When the drum head moves to the right, the particles of the air move further apart, creating a rarefaction. These compression and rarefactions travel through the air as longitudinal waves. When the disturbance in the air reaches our ears, we hear the sound of the drum.
Define the following terms, wavelength, amplitude, frequency, and speed.
- A wavelength is the shortest distance between two adjacent crests or troughs of a transverse wave. It is the distance between two adjacent compressions or rarefactions for longitudinal waves.
- Unit: Wavelength is measured in meters (m).
- The amplitude of a wave is the maximum distance the wave vibrates from its resting position. We can also say that it is the height of a crest or depth of a trough measured from the rest position.
- Unit: Amplitude is measured in meters (m).
- The number of vibrations produced by a vibrating body in one second is called its frequency. Frequency is measured in a unit called hertz. When one wave passes in one second, the frequency is I wave per second or I hertz.
- The distance a wave covers in unit time is called its speed. Speed is measured in meters per second.
Speed=Distance covered/ time (in second)
- The sound of listening is heard after a few seconds of flash, so sound travels low than light.
- Thunder is always heard after we see lightning. It shows that light travels much faster than sound.
Give the relationship b/w speed, wavelength, and frequency.
Relationship b/w speed, wavelength, and frequency:
- The speed, wavelength, and frequency of a wave are related to each other by a mathematical formula speed=wavelength ×frequency:
- We can calculate any one value by knowing the other two values.
What is the audible frequency range of humans?
Audible frequency range:
- The range of frequency that a person can hear is known as the audible frequency range.
- A healthy human ear can hear sounds of frequency from about 20 Hz to 20000 Hz. It is the audible frequency range for humans. Different animals have different audible frequency ranges.
Audible frequency range of different animals
What is meant by pitch and loudness?
- Pitch and loudness are the two charters we can distinguish between pleasant sound and noise.
- It is defined as the highest or lowness of a sound. The sound characteristics deal with a more shrill and less shrill sound. A shrill sound is called a high pith sound; a less shrill sound is called a low one.
- The pith depends upon the frequency of the sound waves. The higher frequency, the higher pith would be.
- Loudness is related to the amplitude of the sound. The larger the amplitude, the louder the sound. Loudness helps distinguish a soft sound from a loud sound of the same frequency unit: the loudness of a sound is measured in units called decibels (dB).
Loudness of sounds:
40 to 45
120 to 1700
Everyday Science Short Questions & Answers (Part-5)
What is meant by a quantity of sound?
- It is the characteristics of the sound which help us differentiate between the sound of the same pitch and loudness.
- During the music performance, there are a lot of sounds of equal pitch and loudness. We can distinguish these musical instruments’ quantity of sound.
What is meant by wind instruments, like a flute?
- A flute is a wind instrument. The flutist blows it to make music. Flutes are hollow pipes and a series of holes. The holes are closed with fingers to control the length of the vibrating column of air in the flute. The flutist changes the sound by opening and closing the holes in the flute. A flute can be made of wood, metal, and plastic.
Q. What are the applications of sound?
- Sounds are very important in our lives. We use many devices which produce different sounds.
- The sound of a doorbell indicates that someone is at the door.
- The sound of a telephone attracts our attention to attend the person online.
3 Security system alarm:
- Some buildings are fitted with security system alarms. The alarm produces a sound to alert people to the danger.
4 Stereo player:
- Listen to your favorite singer using a stereo player.
- A siren warns us about the danger.
We listen to music, news, etc., on the radio.
7 Smoke detector:
- A smoke detector produces alarming beeps on detecting smoke on fire.
How does sound travel?
- Sound always requires a medium to travel. It travels by making longitudinal waves. It makes compression and rarefaction.
What is electricity? What are their types?
- The flow of electrons through the conductor provides electrical energy in the form of an electric current. Electricity can produce light, heat, sound, etc. Electrical energy can help to make our life easier.
There are two kinds of electricity:
1 Static electricity
2 Electric current
What is electric current?
- Electric current: The flow of charges through a conductor is called electric current. Charges travel from one pole to another pole of an electrical source (battery).
- Unit: the unit for electric current is ampere (A) .other smaller units are mill ampere (mA) and microampere (mA). An ammeter measures electric current.
What is an electric circuit?
- An electric circuit is a complete path along which charges. All electrical appliances from our computer to fans and air conditioner contain circuits.
Define conductor and insulators.
- The materials which allow the electric current to pass through them are called conductors. Metals, such as copper, silver, and iron, are good conductors.
- The materials which do not conduct electricity are called insulators. Rubber, glass, sand, plastic, and wood are insulators.
What are the different types of electric circuits? Explain them or explain series circuits and parallel circuits?
Types of electric circuits:
- There are several kinds of circuits. But we shall discuss its two main types, i.e., series circuits and parallel circuits.
- If all components are connected in a single loop, it is a series circuit.
- There is only one path for the current to flow in a series circuit.
- The amount of current that flows through each circuit component (bulb) is the same.
Disadvantages of the series circuit:
There are a few disadvantages of the series circuit:
There is only one path for the current to flow. A break at any path of the circuit stops the current flow in the whole circuit.
The light of bulbs in a series circuit barns dim as more bulbs are added.
(b) Parallel circuits:
If the components are connected in two or more loops, it is a parallel circuit.
There is more than one path for the current to flow in a parallel circuit.
The current flowing through the different parallel circuit branches may be the same or different. But the current in each branch is less than the total current flowing out from the electrical source battery.
Advantages of the parallel circuits:
Parallel circuits have some advantages over a series circuit.
There is more than one path for the current to flow. A break in any branch of the circuit stops the current from flowing through that branch only.
The brightness of the light bulbs is not affected as more branches are added to a parallel circuit.
How the energy transfer takes place in an electrical circuit?
- The energy of moving electric charges with a circuit is called electrical energy.
- This energy is brought to our homes by electrical circuits. Some of the energy dissipates into heat energy.
- A light bulb transfers electrical energy to light energy. Electric bells are stereo players that transfer electrical energy to sound energy.
- A heater gives us heat by using electric energy. A fan converts electrical energy to mechanical energy.
Explain how the charges flow in a circuit or explain how the potential difference or voltage is responsible for the flow of charges, explain with experiments.
- The difference of potential between two points in a circuit or battery is called potential difference or voltage.
- Potential difference is measured in volts(v): potential difference causes the charges to move through the conductor. We can explain it with the help of an experiment.
- The flow of electrons through a conductor (wire) can be compared to water flow in a pipe. Connect two cans of water, one on the floor from a higher level to the lower level. The potential energy of water in the can at the higher level causes the water flow. Similarly, current flows from higher electric potential to lower electric potential.
Everyday Science Short Questions & Answers (Part-6)
- Resistance is a measure to know how difficult it is for an electric current to pass through a material.
The resistance of a wire depends on n:
- Length of the wire
- The thickness of the wire
- Type of material and
- The temperature of the wire.
Define and explain ohm’s law.
- A German scientist, George Simon ohm, discovered the relationship between voltage, current, and resistance. Ohm’s law states that” the current passing through a conductor I directly proportional to the potential difference across its ends.”
- Where ‘v’ is the potential difference, ‘I’ is the current, and; R; is the constant called resistance. The above equation shows that resistance is equal to the voltage divided by the current.
Unit: Scientists use ohm as the unit of resistance.
Which instrument is used to measure the current or explain the ammeter?
- An Ammeter is a device used to measure the amount of current in an electric circuit. It is connected to the circuit in series so that the full current passes through it. An ammeter does not change the amount of the current in a circuit because it has very low resistance.
What is Voltmeter, and for what purpose is it used?
- A voltmeter is a device to measure the voltage (potential difference) in a circuit. One is connected to the circuit in series so that the full current passes through it. An ammeter does not change the amount of the current in a circuit because it has very low resistance.
What is Voltmeter, and for what purpose is it used?
- A voltmeter is a device to measure the voltage (potential difference). It is connected in parallel with the circuit. The current does not flow through a voltmeter because it has very high resistance.
What is Millimeter?
- A millimeter can measure resistance, voltage, and small currents.
What is Electrical Power? What are its units?
- All electric devices such as fans, blenders, computers, etc., convert electrical energy into other forms of energy. Electrical power is the rate at which a device converts electrical energy into another form of energy. Its unit is the watt (w).
Kilowatt-hour (K w h):
Our electricity bill shows the amount of energy we use during one month. It is taken as kilowatt-hour. One kilowatt-hour is 1 unit on an electricity meter. It is the amount of energy used up when an electrical appliance of 1,000 watts wok for 1 hour.
How can you say that electricity is flowing through the circuit?
- We cannot see the electrical energy flowing in the circuit. But any of the following changes can tell us that electricity is flowing through the circuit.
Heating effect of the current:
- When electric current makes it hot, light or spark is produced when the wire becomes very hot. We use many applications in our homes that convert current to heat.
Chemical effect of the current:
- When current flows through a solution, it can break up the solution into its components.
- Electrolysis is the breakdown of a compound into its components by passing electricity.
- Electricity is used to coat a metal object with a thin layer of another metal. This process is called electroplating, e.g., the rim of bicycles.
Magnetic effect of the current:
- An electric current can also produce a magnetic effect wire.
- A coil of wire around a piece of iron behaves like a bar magnet when an electric current is passed through it. Such magnets are called electromagnets. It stops acting as a magnet when electricity stops flowing through it.
- The electromagnets present the earpiece of the telephone to convert electrical signals into sound. Electromagnets are also used to produce a magnetic field in electric motors.
How is electricity dangerous?
The danger of electricity:
- Electricity is part of our everyday life. Sometimes it can be dangerous. As the electric shock is a lot painful and dangerous. Here’s what can happen:
- the muscles tighten up, making it impossible to pull away from the circuit.
- Lungs constrict, making them hard to breathe.
- Burns occur when the electricity enters and leaves the body.
What do you mean by short circuit?
- A large current passes through the wires, which causes the wires to overheat quickly. A fire may start as a result of a short circuit.
What are safety rules which protect us from electricity hazards?
- Do not touch wires with wet hands.
Fallen power lines:
- Never touch fallen power lines.
- Never enter metal objects in sockets.
Overloading of power socket:
- Never overload a power socket.
Do not touch electrocuted:
- If a person has been electrocuted, do not touch the person’s body. Use a non-metallic object to move the victim away from the electric wire.
Enlist the instruments used to remain safe from the electricity dangers.
- Electricity is dangerous if it is mishandled. Following are the precautionary instruments that are useful to protect us from the danger of electricity.:
- Line and the neutral wire.
- Main switch
- Earth wire
- Three in plug 6. E.L.C.B. (Earth leakages).
- M.C.B.s (Miniature circuit breaker) circuit breaker.
What is the live and neutral wire? Explain their role?
Live and neutral wires:
- The cable connected to the electricity meter consists of two electrical wires, one is life, and the other is neutral. Current flows in live or hot wire. These wires are called mains.
What do you know about the main switch?
- The main switch is introduced to the live wire coming from the meter or main supply. When the main switch is pushed ON, it connects the electric supply to the whole electric circuit. When it is pushed OFF, it cuts off the electric supply.
Everyday Science Short Questions & Answers (Part-7)
What is the fuse? Explain it”?
- A fuse is a thin and small piece of a conductor wire. It is connected in the path of a live wire. It gets heated up and melts on the passing of an extra-large amount of current. Fuses are used to protect houses against short circuits and overloading.
What is a miniature circuit breaker and earth leakage circuit breaker?
M.C.B.S. (Miniature circuit breakers):
- Replacing the fuse, again and again, is not a pleasant experience. So engineers have developed the alternatives to fuses, i.e., miniature circuit breakers(M.C.B.s). An (M.C.B.s) is a small electromagnet switch that works like a fuse but does not blow out. It breaks the circuit by tripping when a current more than its rating passes through it.
E.L.C.B. (Earth leakage circuit breaker):
- An earth leakage circuit breaker (E.L.C.B.) is a safety device used in electrical installations to prevent a shock. An E.L.C.B. is an electromagnetic switch. It quickly turns off the power when the current flowing through the earth wire exceeds the limit. If someone tries to use the faulty electric appliance, an E.L.C.B. breaks the circuit at once.
What is the role of an earth wire?
- An additional earth wire protects us from electric shocks. If a short-circuiting occurs in a device. Then current will begin to flow through low resistance earth wire. In this way, a person will be protected if he touches faulty devices. Earth wire is buried in the ground.
Explains three-pin plug?
- In three pin plug, two pins connect the appliance to the supply while the third pin connects the metal cover of an electric appliance to the earth wire. In short-circuiting, this third pin helps send a large amount of current into the ground.
Define solar system and universe.
- Our solar system is a part of our universe. The universe is very vast. Scientists say that universe is expanding. They also say that there are more than 200,000,000,000 billion stars.
- The universe is all of space and everything in it. Most of the universe is space. Our solar system is an externally small part of the universe. Many theories are given to explain the origin of the universe. Those theories result from human efforts in understanding the nature and origin of the universe.
What are the different theories of the creation of the universe?
An Islamic theory of the creation of the universe:
- According to Islam and other Abrahamic religions, the universe was created by Allah (S.W.T.). According to the holy Quran, Allah said that the universe was created. Scientists have been presenting different theories of the creation of the universe from time to time.
The big bang theory:
- According to the big band theory, about 10 to 20 billion years ago, the universe was packed into one giant fireball. Then a tremendous explosion started the expansion of the universe. The extraordinary explosion is known as the big bang. This explosion spread matter and energy in all directions. After the big bang, the universe assumed the form of huge clouds of expanding hot and contracting gasses. With time, the matter cooled, and the force of gravity pulled together the particle of matter to form stars and galaxies.
Explain the evidence to support the big bang theory.
Evidence to support the big bang:
- The big bang theory was first proposed in 1927 by a Peist, Gorge Lemaitre of Belgium. This theory was supported by the discoveries of Edwin Hubble and noble prize-winning scientists Arno Penzias and Robert Wilson.
Edwin Hubble found experimental evidence to support the big bang theory. He found that distant galaxies in every direction are going away from us at a very high speed. This observation is acceptable in the universe that began in the huge explosion.
The big bang theory also predicts the existence of cosmic background radiation(glow left over from the explosion itself.) this radiation was discovered in 1964 by Arno Penzias and Robert Wilson. They later won the noble prize for this discovery. Although the big bang theory is widely accepted, it probably will never be proved. It cannot answer many questions about the occurrence of the big bang.
What are stars?
- Many twinkling lights in the night in the sky one observe. Some of these lights come from objects in the space called starts.
- The sun is also a star. Beyond the solar system, billions and billions of stars are present in space. Every star is a ball of glowing gasses which emit energy in the form of heat and light. Astronomers say that the sun is a medium-sized star. Some stars are much larger, and some are smaller.
Explain the reason for the different colors of stars.
Colors of starts:
- Stars emit heat and light in different amounts, so stars have different temperatures. The color of a star is related to its temperature. The coolest stars have about2800°C temperature on their surfaces and appear red. The hottest stars have 28000°C OR higher temperatures and look blue. The in-between stars’ temperatures have orange, yellow, and white colors.
- The sun is a yellow star. It has a temperature of 5,500 to 6000°C at its surface. Stars that are a little colder than the look orange. Stars that are a little hotter than the sun appear white. See the table. Blue stars are hotter than red stars.
Table: Color and temperature of some stars.
Name of star
What are the reasons for the brightness of the star?
The brightness of stars:
The brightness of stars depends on two factors.
Distance of the star from the earth:
- We can estimate how far away each street light is by its apparent brightness. Does this work with stars?
Amount of energy the star emits:
- Imagine you are looking at two stars that are the same distance from the earth. The stars which emit a greater amount of energy will seem brighter than the other. Now imagine two stars that emit an equal amount of energy. One is near the earth both stars will show different brightness.
How the distance between the star is measured?
- The stars are very far away from us. They are a great distance from each other. The distance between them is so great that we cannot measure it in kilometers. So large unit called light-year is used to measure the distance.
- A light-year is the measurement of the distance that light covers in one year with a speed of 300000 kilometers per second.
- It seems that the alight year is a very long distance. The sun is our closest star in one galaxy. The next closest is the proximal star, which is 4.2 light-years away from us. We can also say that light of this star will take 4.2 years to reach the earth.
- A galaxy is a very large group of stars, nebulae, gases, dust, and planets. A galaxy may contain billions of stars. Astronomers have used special instruments to identify about one billion galaxies. Our solar system is a part of the milky watt galaxy. There are many types of galaxies in the universe. Scientists classify galaxies into three main types based on shape.
Everyday Science Short Questions & Answers (Part-8)
Explains spiral galaxies.
- A galaxy that has a flat disk-like shape with a bulge in the center is called a spiral galaxy.
Spiral galaxies many have a few or many spiels or curved arms.
Many dust and gases are present in these galaxies.
The milky Way and Andromeda are spiral galaxies. The Milky Way galaxy contains 100 to 200 billion stars. The sun is about 30,000 light-years away from its center. The Milky Way galaxy is moving at 2200000 kilometers per hour in space.
What do you mean by the birth of a star? Explain it.
- The great clouds of gases and dust are present in galaxies. Each of these clouds is called a nebula. Stars are born in nebulae.
- A nebula collects more dust and gases during travel through space. The gases and dust particles are packed into a hot spinning ball of matter. Such a ball is called a protester. With time protesters began to produce a great amount of energy. At this stage, a protester is called a star. Now it emits energy and heat all the time.
How do the stars die off?
- The matter of the stars changes into energy. This radiant energy is released into space. In this way, the stars will die with time. Sun is also releasing energy in space by changing its matter into energy in the same way the sun will die.
Define and explain elliptical galaxies and irregular galaxies.
These are elliptical-shaped galaxies.
These galaxies do not rotate as spiral galaxies around their axis.
An elliptical galaxy contains fewer amounts of dust and gases than a spiral galaxy.
Trillion stars may bepresent in an elliptical galaxy.
New stars cannot form in most elliptical galaxies. Most of them only contain old stars.
These galaxies have no definite shape.
The stars in an irregular galaxy do not appear to be grouped in any set shape.
These galaxies have many shapes and sizes.
The clouds of Magellan are an irregular galaxy. It is a very small galaxy near the Milky Way.
These galaxies are not very common.
What do you mean by the life of stars?
- The universe is finite. Stars have life cycles with a beginning, a middle, and a future. They are born, get changed, and die. So the stars have lived for billions of years.
What are constellations? How do people think about constellations?
- A constellation is a group of stars with a definite pattern or arrangement. Each constellation has a different pattern. Each constellation is found in certain places in the sky.
Use of constellation:
- Constellations were very important to people long ago. These people use the night sky to bel time and seasons. Crop planting festivals and other events were planned according to the movement of the stars in the constellation. People long ago named the star patterns they saw for an object, animals, or famous people. People also make strain stories about constellations. We can observe many constellations at night.
What is a big dipper?
- The big dipper is a famous constellation. There are seven visible stars in the big dippers. Four stars make the bowl of the handle. The two bright stars on the end of the big dipper bowl point to the pole star. This star help in finding directions.
What do you know about Cassiopeia?
- Cassiopeia is a constellation that seems to move around the pole star all the year. Cassiopeia is on the opposite side of the pole star from the big dipper and about the same distance away.
- The five brightest stars in Cassiopeia form the shape of the capital letter M or W. people long ago thought this star pattern looked like a queen sitting on her throne.
What is the Leo constellation?
- Leo, the Leo, is a famous constellation seen in March, April, and May. Stars in this constellation are arranged in the shapes of a backward question mark and a triangle. We can also find this constellation with the help 0of two b=right stars in the big dipper. If we look north, these two stars indicate pole stars. If we look south, these two stars point to the Leo constellation.
What do you mean by red giant stage and dwarf stage or explain the life cycle of a low mass star?
Red giant stage:
- Our star ( the sun)_ has passed five billion years while emitting energy. After the next five billion years, the hydrogen in the sun’s core may be used up. The sun starts to collapse. Its core will become denser and hotter, and the sun will swell in size. It will become a red giant. The sun will be a red giant for only about five hundred million years.
- By an by the sun in the form of a red giant will coal and gravity will make it collapse4 in word. Our star will become a white dwarf at this stage. Eventually, the sun will become a black chunk of very dense matter. It will not emit light anymore. This last stage of a star’s life is called a black dwarf.
What is a black hole, and how is it formed?
Explain the life of a massive star?
- Almost six times more massive than the sun, the stars are called massive stars.
The life span of a massive star:
- The massive star has a shorter life span than the sun or other low mass stars. Hydrogen present in their core is used up at a much fast speed, so only after 50 to 100 million years after no hydrogen will leave in the core of a massive star.
- When hydrogen is finished in the core of a star, the core collapses, and the star becomes 1000 times greater than its original size. It is now called supergiant.
- As time passes, the supergiant becomes so dense that it cannot bear the pressure of outer layers. The outer layers crash in word with a tremendous explosion called a supernova.
- At the supernova time, the star’s light becomes much more than all other remaining lift in the galaxy.
- At the supernova stage, the great shells of the gases fly off the star. Only the tiny core of the star remains left. This core contains only neutrons, so it is called a neutron star. It is extremely dense.
- Sometimes after the supernova explosion, the massive star becomes a black hole. It is so dense that nothing can escape from its very strong gravity. A black hole is the last stage of the life cycle of a massive star.
Explain the structure and function of the telescope?Telescope:
- A telescope is a device used to see a distant object appear very close. Many more stars can be seen with the help of a telescope than with the naked eye.
A simple telescope has two lenses.
(1). Objective lens:
- The objective lens collects light from a distant object and brings that light or image to the point of focus.
(2). Eyepiece lens:
- An eyepiece lens takes the light from the objecting lens and magnifies it.
What are the safety tips for observing the sun?
- The sun emits radiation, so it is dangerous to view directly into the sun. It can damage our eyes. So take the following safety measure.
Use of pinhole:
- A pinhole or a small opening is used to view the sun’s image on a screen placed a half-meter or more beyond the opening.
Use of sheet of x-rays:
- Use two or three sheets of x-rays film for viewing the sun.
- No filter is safe for use with any optical devices, i.e., telescope, binoculars, etc.