Tag: physics

Questions Related to physics

Compton effect is associated with

detection and recording of x-ray images option c: imaging physics

  1. $\alpha -$ rays

  2. $\beta -$rays

  3. Positive rays

  4. X-rays

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Correct Option: D
Explanation:

Compton scattering is an inelastic scattering of a photon by a quasi-free charged particle, usually an electron. It results in a decrease in energy (increase in wavelength) of the photon (which may be an X-ray or gamma ray photon), called the Compton effect. Part of the energy of the photon is transferred to the recoiling electron. Binding energy is equal to work function of metal. In most of metals, the threshold frequency is equal to that of ultravoilet light. So Compton effect is associated with X-rays.

Compton shift refers to :

detection and recording of x-ray images option c: imaging physics

  1. Meson

  2. Photon

  3. Proton

  4. Positron

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Correct Option: C
Explanation:

Compton shift refers to proton.

Which of the following phenomenon supports the quantum nature of light?

detection and recording of x-ray images option c: imaging physics

  1. Compton effect

  2. Interference

  3. Diffraction

  4. Polarisation

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Correct Option: A
Explanation:

The wave nature of light is exhibited by interference, diffraction and polarisation of light.
Compton effect is the strongest evidence to show the particle nature of light, and hence the quantum theory of light.

So, the answer is (A).

According to photon theory of light which of the following physical quantities  associated with a photon do not / does not change as it collides with an electron is vacuum:

detection and recording of x-ray images option c: imaging physics

  1. Energy and momentum

  2. Speed and momentum

  3. Speed only

  4. Energy only

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Correct Option: A
Explanation:
Under the photon theory of light, a photon is a discrete bundle (or quantum) of electromagnetic (or light) energy. Photons are always in motion and, in a vacuum, have a constant speed of light to all observers, at the vacuum speed of light (more commonly just called the speed of light) of $c = 2.998 \times 10^8 m/s$

According to the photon theory of light, photons .
move at a constant velocity, $c = 2.9979 \times 10^8 m/s$ (i.e. "the speed of light"), in free space
have zero mass and rest energy.

Carry energy and momentum, which are also related to the frequency $\mu$ and wavelength $\lambda$ of the electromagnetic wave by $E = h \mu$ and $p = \dfrac{h}{\lambda}.$

Can be destroyed/created when radiation is absorbed/emitted.

Can have particle-like interactions (i.e. collisions) with electrons and other particles, such as in the Compton effect

In Rutherford scattering of $  \propto  $ - particle experiment, transfer of maximum energy is possible only when the scattering angle is

detection and recording of x-ray images option c: imaging physics

  1. $ 360^{\circ} $

  2. $ 180^{0} $

  3. $ 90^{0} $

  4. $ 30^{0} $

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Correct Option: A

The apparent wavelength of the light from a star moving away from the earth is 0.2% more than its actual wavelength. Then the velocity of the star is 

detection and recording of x-ray images option c: imaging physics

  1. $6 \times 10^7 \ ms^{-1}$

  2. $6 \times 10^6 \ ms^{-1}$

  3. $6 \times 10^5 \ ms^{-1}$

  4. $6 \times 10^4 \ ms^{-1}$

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Correct Option: C

From the $\alpha$-particle scattering experiment, Rutherford concluded that

detection and recording of x-ray images option c: imaging physics

  1. $\alpha$- particles can come within a distance of the order of $10^{-14}$ m of the nucleus.

  2. The radius of the nucleus is less than $10^{-14}$ m

  3. Scattering follows coulomb's law

  4. The positively charged parts of the atom move with extremely high velocities

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Correct Option: B

X-rays of wavelength of $22\ pm$ are scattered from a carbon target at an angle of $85^0$ to the incident beam. The compton shift for X-rays is $(cos\ 85^0=0.088)$

detection and recording of x-ray images option c: imaging physics

  1. $2.2\ pm$

  2. $1.1\ pm$

  3. $0.55\ pm$

  4. $4.4\ pm$

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Correct Option: A
Explanation:

Compton shift is given as $\Delta \lambda =\dfrac{h}{mc}(1-cos \phi )=\dfrac{6.62\times 10^{-34}Js}{9.1\times 10^{-31} Kg\times 3\times 10^8m/s}(1-cos 85^0)$ 

where $m$ is the mass of electron and $h$ is Planck's constant with $c$ as speed of light in air.
On calculation we get the shift as $\Delta \lambda =2.2\times 10^{-12}meter=2.2pico meter$
Option A is correct.

Find the correct statement

detection and recording of x-ray images option c: imaging physics

  1. A free electron can absorb a photon completely.

  2. A free electron can not absorb a photon completely.

  3. A free electron can not exist.

  4. A free neutron can exist for a long time

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Correct Option: B
Explanation:

According to Compton's scattering 


$\displaystyle \Delta \lambda =\dfrac{h}{mc}(1-\cos \phi )$ 

which shows a free electron can not absorb a photon completely. If a free electron absorb a photon there is nothing to share the recoil. So momentum will not conserve which is not possible.
So, the answer is option (B).

For Compton effect with visible light the observed Compton shift is

detection and recording of x-ray images option c: imaging physics

  1. Very large because the electrons appear free

  2. Very small because the electrons appear free

  3. Is almost zero because the electrons appear bound

  4. Less than zero

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Correct Option: C
Explanation:

In compton scattering it is necessary that the energy of the photon should be very much greater than binding energy of electron. Binding energy is equal to work function of metal. In most of metals, the threshold frequency is equal to that of ultravoilet light that is why we do not observe comption effect with visible light.