Fsc part 2 online preparation for physics chapter 19 (modern physics)

Online Short Questions For Chapter 8 "12th Class Physics Chapter 8 Short Questions Preparation "

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Physics - 12th Class Physics Chapter 8 Short Questions Preparation

Question # 1

Define Compton effect.

Ans 1: The phenomena of increase in wavelength of x rays photon scattered by loosely bound electrons from a graphite target is called Compton Effect.

Question # 2

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Ans 1: Since intensitynumber of electrons.
and bright lightis more intensethan dimmer one.So bright light will ejects more electrons than dimmer light.

Question # 3

Is it possible to create a single electron from energy?

Ans 1: No it is not possible to create single electron from energy.Because electron has negative charge and photon has no charge,

Question # 4

Differentiate between inertial and non-inertial frame of reference.

Ans 1: A coordinate system in which the law of inertia is valid is called inertial frame of reference.It is non-accelerated frame of reference.
Ans 2: A coordinate system in which the law of inertia is not valid is called non-inertial frame of reference.It is accelerated frame of reference.

Question # 5

Define pair production and annihilation of matter.

Ans 1: Pair production:The change of very high energy photon into an electron,positron pair is called pair production.
Annihilation of matter:When a positron comes close to an electron,they annihilation and produce two photons in the gamma rays range.It is called annihilation of matter.

Question # 6

Will higher frequency of light ejects greater number of electrons than low frequency of light?

Ans 1: No it will not,The number of ejected electrons depend upon the intensity of light.They are independently of frequency.

Question # 7

What do you understand by work function and stopping potential?

Ans 1: The minimum amount energy required to remove an electron from the surface of a metal is called work function.
And the stopping potential is the potential difference applied to stop the electrons from being ejected from the surface when the light falls on it.

Question # 8

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Ans 1:
1. The pulse rate of the person inside the spaceship moving with large velociety will decrease.
2. The pulse rate of the people on the earth with respect to the person inside the spaceship with large velocity will increase.

Question # 9

Differentiate between special theory of relativity and general theory of relativity.

Ans 1: The special theory of relativity treats problem involving inertial or non accelerating frame of reference.
Ans 2: The general theory of relativity treats problem involving frames of reference accelerating with respect to one another.

Question # 10

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

Ans 1: If light were simple a wave like phenomena ,then increasing the intensity and thereby increasing the total energy failing on the surface would be expected to eventually provide enough energy to release electron no matter what the frequency .Furthermore in the classical picture one would expect the maximum energy of the emitted electrons to depend on the intensity of light--but it does not.So this is evidence that light behaves as if it were a particle.

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Prepare Complete Set Wise Questions For Chapter 8 "12th Class Physics Chapter 8 Short Questions Preparation "

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12th Class Physics Chapter 8 Short Questions Preparation - Set 1

Question # 1

Define Compton effect.

Ans 1: The phenomena of increase in wavelength of x rays photon scattered by loosely bound electrons from a graphite target is called Compton Effect.

Question # 2

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Ans 1: Since intensitynumber of electrons.
and bright lightis more intensethan dimmer one.So bright light will ejects more electrons than dimmer light.

Question # 3

Is it possible to create a single electron from energy?

Ans 1: No it is not possible to create single electron from energy.Because electron has negative charge and photon has no charge,

Question # 4

Differentiate between inertial and non-inertial frame of reference.

Ans 1: A coordinate system in which the law of inertia is valid is called inertial frame of reference.It is non-accelerated frame of reference.
Ans 2: A coordinate system in which the law of inertia is not valid is called non-inertial frame of reference.It is accelerated frame of reference.

Question # 5

Define pair production and annihilation of matter.

Ans 1: Pair production:The change of very high energy photon into an electron,positron pair is called pair production.
Annihilation of matter:When a positron comes close to an electron,they annihilation and produce two photons in the gamma rays range.It is called annihilation of matter.

Question # 6

Will higher frequency of light ejects greater number of electrons than low frequency of light?

Ans 1: No it will not,The number of ejected electrons depend upon the intensity of light.They are independently of frequency.

Question # 7

What do you understand by work function and stopping potential?

Ans 1: The minimum amount energy required to remove an electron from the surface of a metal is called work function.
And the stopping potential is the potential difference applied to stop the electrons from being ejected from the surface when the light falls on it.

Question # 8

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Ans 1:
1. The pulse rate of the person inside the spaceship moving with large velociety will decrease.
2. The pulse rate of the people on the earth with respect to the person inside the spaceship with large velocity will increase.

Question # 9

Differentiate between special theory of relativity and general theory of relativity.

Ans 1: The special theory of relativity treats problem involving inertial or non accelerating frame of reference.
Ans 2: The general theory of relativity treats problem involving frames of reference accelerating with respect to one another.

Question # 10

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

Ans 1: If light were simple a wave like phenomena ,then increasing the intensity and thereby increasing the total energy failing on the surface would be expected to eventually provide enough energy to release electron no matter what the frequency .Furthermore in the classical picture one would expect the maximum energy of the emitted electrons to depend on the intensity of light--but it does not.So this is evidence that light behaves as if it were a particle.

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12th Class Physics Chapter 8 Short Questions Preparation - Set 2

Question # 1

What are the measurement on which two observers in relative motion will always agree upon?

Ans 1: Two observe in relative motion will always agree upon
1. Force
2. Acceleration

Question # 2

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Ans 1: Since intensitynumber of electrons.
and bright lightis more intensethan dimmer one.So bright light will ejects more electrons than dimmer light.

Question # 3

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Ans 1:
1. The pulse rate of the person inside the spaceship moving with large velociety will decrease.
2. The pulse rate of the people on the earth with respect to the person inside the spaceship with large velocity will increase.

Question # 4

Is it possible to create a single electron from energy?Explain

Ans 1: No it is not possible to create a single electron from energy.Creation of single electron will be against the law of conservation of charge and the law of conservation of momenteum.In pair production an electron positron pair is produces.

Question # 5

Define pair production and annihilation of matter.

Ans 1: Pair production:The change of very high energy photon into an electron,positron pair is called pair production.
Annihilation of matter:When a positron comes close to an electron,they annihilation and produce two photons in the gamma rays range.It is called annihilation of matter.

Question # 6

We do not notice the de-Broglie wavelength for a pitched cricket ball.Explain why?

Ans 1: According to de-Broglie hypothesis
λ =h/mv
As cricket ball has large mass,therefore wavelength of wavelength associated with it is so small that is not detectable.

Question # 7

When light shine on surface,is momentum transferred to metal surface?

Ans 1: Yes when light shine on surface,momentum is transferred to metal surface and also the energy.So metal is heated up.

Question # 8

State uncertainty principle.

Ans 1: The product of uncertainty in the measurement of momentum and uncertainty in the measurement of position of an electron is approximately equal to Planck's constant.
The product of uncertainty in the measurement of energy and uncertainty in the measurement of time of an electron is approximately equal to Planck's constant.

Question # 9

Define Compton effect.Write formula of Compton shift for scattering angle.

Ans 1: When X-rays are scattered by loosely bound electrons from a graphite target,the phenomena of change in wavelength is known as Compton Effect.Compton shift for scattering angle is given
$\lambda '-\lambda ={\frac {h}{m_{e}c}}(1-\cos {\theta }),$

Question # 10

Will higher frequency of light ejects greater number of electrons than low frequency of light?

Ans 1: No it will not,The number of ejected electrons depend upon the intensity of light.They are independently of frequency.

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12th Class Physics Chapter 8 Short Questions Preparation - Set 3

Question # 1

Which has the lower energy quanta,radio waves or x rays?Explain

Ans 1: Energy of quanta is given as E=hf-hc/lamda
Radio waves length has longer wavelength,Therefore radio waves has lower energy quanta.

Question # 2

What are black body radiations and how can you get a black body?

Ans 1: An objects that absorbs all radiations falling on it,at all wavelength is called a black body.
When a body is heated ,it emits radiation its emission is called black body.
Black body is solid that has hollow cavity within it and a small hole through which radiations can enter or escape.The inside is blackened with suit to make it as good an absorber and as a bad reflector as possible.

Question # 3

When does light behaves as a wave?When does light behaves as a particle?

Ans 1: Light behave as a wave when it propagates from one place to other and light behave as a particle when it interacts with matter,Light behaves as a wave in interference and diffraction,Light behaves as a particle in photoelectric and Compton effect.

Question # 4

Can a pair production take place in vacuum?Explain

Ans 1: No,pair production can not take place in vacuum.
In order to conserve the momentum and energy,their presence of heavy nucleus is essential,The vacuum has no particle or heavy nucleus,Therefore pair production can not take place in vacuum.

Question # 5

Will higher frequency of light ejects greater number of electrons than low frequency of light?

Ans 1: No it will not,The number of ejected electrons depend upon the intensity of light.They are independently of frequency.

Question # 6

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Ans 1: Since intensitynumber of electrons.
and bright lightis more intensethan dimmer one.So bright light will ejects more electrons than dimmer light.

Question # 7

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

Ans 1: If light were simple a wave like phenomena ,then increasing the intensity and thereby increasing the total energy failing on the surface would be expected to eventually provide enough energy to release electron no matter what the frequency .Furthermore in the classical picture one would expect the maximum energy of the emitted electrons to depend on the intensity of light--but it does not.So this is evidence that light behaves as if it were a particle.

Question # 8

What advantage of an electron microscope has over an optical microscope?

Ans 1:
- Resolving power of an electron microscope is 1000 times greater than that of optical microscope.
- Magnification of an electron microscope is also about 1000 times greater than that of optical microscope.
- 3-D image of remarkable quality can be obtained by electron.

Question # 9

Define work function and threshold frequency.

Ans 1: The minimum amount of energy required to remove electrons from a metal surface is called work function of this metal.
The minimum frequency below which photoelectric effect can not occur from a metal surface is called threshold frequency of this metal.

Question # 10

The rest mass of photon is zero.Is its momentum also zero?

Ans 1: No,The rest mass of photon is zero.It travels in the form of small energy packets which are of equal wavelength .When it is in motion,it possesses some mass.So it which it will also have momentum.

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Physics

19th Chapter

12th Class Physics Ch 19 Preparation

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Fsc part 2 online preparation for physics chapter 19 (modern physics)

Online Short Questions For Chapter 8 "12th Class Physics Chapter 8 Short Questions Preparation "

Physics - 12th Class Physics Chapter 8 Short Questions Preparation

Define Compton effect.

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Is it possible to create a single electron from energy?

Differentiate between inertial and non-inertial frame of reference.

Define pair production and annihilation of matter.

Will higher frequency of light ejects greater number of electrons than low frequency of light?

What do you understand by work function and stopping potential?

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Differentiate between special theory of relativity and general theory of relativity.

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

Prepare Complete Set Wise Questions For Chapter 8 "12th Class Physics Chapter 8 Short Questions Preparation "

Set 1

Set 2

Set 3

12th Class Physics Chapter 8 Short Questions Preparation - Set 1

Define Compton effect.

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Is it possible to create a single electron from energy?

Differentiate between inertial and non-inertial frame of reference.

Define pair production and annihilation of matter.

Will higher frequency of light ejects greater number of electrons than low frequency of light?

What do you understand by work function and stopping potential?

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Differentiate between special theory of relativity and general theory of relativity.

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

12th Class Physics Chapter 8 Short Questions Preparation - Set 2

What are the measurement on which two observers in relative motion will always agree upon?

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

If you are moving in a spaceship at very high speed relative to the earth.Would you notice difference(a)In your pulse rate(b)In the pulse rate of people on the earth?

Is it possible to create a single electron from energy?Explain

Define pair production and annihilation of matter.

We do not notice the de-Broglie wavelength for a pitched cricket ball.Explain why?

λ =h/mv

When light shine on surface,is momentum transferred to metal surface?

State uncertainty principle.

Define Compton effect.Write formula of Compton shift for scattering angle.

Will higher frequency of light ejects greater number of electrons than low frequency of light?

12th Class Physics Chapter 8 Short Questions Preparation - Set 3

Which has the lower energy quanta,radio waves or x rays?Explain

What are black body radiations and how can you get a black body?

When does light behaves as a wave?When does light behaves as a particle?

Can a pair production take place in vacuum?Explain

Will higher frequency of light ejects greater number of electrons than low frequency of light?

Will the bright light ejects more from metal surface than dimmer light of tha same colour?

Photoelectric effect give the evidence of the particle nature of light,Explain it how?

What advantage of an electron microscope has over an optical microscope?

Define work function and threshold frequency.

The rest mass of photon is zero.Is its momentum also zero?

12th Class Physics Ch 19 Preparation