Tag: option c: imaging

Questions Related to option c: imaging

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.

A strong argument for the particle nature of cathode rays is that they

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

  1. travel through vacuum

  2. cast shadow

  3. get deflected by electric and magnetic field

  4. produce fluroscence

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Correct Option: C

A photon of frequency f under goes compton scattering from an electron at rest and scatters through an angle $\theta$. The frequency of scattered photon is ${ f }^{ ' }$ then

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

  1. ${ f }^{ ' } > f$

  2. ${ f }^{ ' } = f$

  3. ${ f }^{ ' } < f$

  4. None of these

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Correct Option: C
Explanation:

After scattering the wavelength of scattered photon increases due to the loss of energy and hence, the frequency decreases.
So, $f'<f$
So, the answer is option (C).

The particle nature of cathode rays is proved by

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

  1. Their deflection under magnetic/ electric field

  2. Colour of glow in gas discharge tube.

  3. Their propagation along a straight line.

  4. All of these.

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Correct Option: A

In the case of Compton effect, which of the following is applicable ?

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

  1. Energy conservation

  2. Momentum conservation

  3. Charge conservation

  4. All of the above

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Correct Option: B

If h is planks constant, $m _o$ is rest mass of electron and c is the speed of light in vacuum, the S.I unit of $\dfrac{h}{m _{0}C}$ is

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

  1. $A^{0}$

  2. Js

  3. Ns

  4. m

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Correct Option: D
Explanation:

de Broglie wavelength,

$\lambda =\dfrac { h }{ p } =\dfrac { h }{ mv } $
and unit of $\lambda$ is $m$.
So, the answer is option (D).