If V be the accelerating voltage, then the maximum frequency of continuous x-rays is given by

1.  $\frac{eh}{V}$

2.  $\frac{hV}{e}$

3.  $\frac{eV}{h}$

4. $\frac{h}{eV}$

The maximum kinetic energy of photoelectron emitted from the surface of work function f due to incidence of light of frequency n is E. If the frequency of incident light is doubled, then maximum kinetic of emitted photon will be

1.  2E

2.  2E - f

3.  2E + f

4.  2E + 2f

What is the de-Broglie wavelength associated with an electron accelerated through a voltage of 900 V?

1.  $0.31 \stackrel{\mathrm{o}}{\mathrm{A}}$

2.  $0.41 \stackrel{\mathrm{o}}{\mathrm{A}}$

3.  $0.5 \stackrel{\mathrm{o}}{\mathrm{A}}$

4.  $0.16 \stackrel{0}{\mathrm{A}}$

What is the de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m?

1. $\frac{h}{\sqrt{mkT}}$

2. $\frac{h}{\sqrt{3mkT}}$

3. $\frac{2h}{\sqrt{3mkT }}$

4. $\frac{2h}{\sqrt{mkT}}$

If an electron of mass m with a de-Broglie wavelength of l falls on the target in an X-ray tube, the cut-off wavelength ( λ₀) of the emitted X-ray will be:

1. ${\lambda }_0=\frac{2mc{\lambda }^2}{h}$         

2. ${\lambda }_0=\frac{2h}{mc}$

3. ${\lambda }_0=\frac{2m^2{c}^2{\lambda }^3}{h^2}$       

4. ${\lambda }_0=\lambda$

Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectron will reach the anode A, if the stopping potential of A relative to C is

1. +3 V

2. +4 V

3. - 1V

4. -3 V

When a metallic surface is illuminated with radiation of wavelength $\lambda$, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2$\lambda$, the stopping potential is $\frac{V}{4}$ .The threshold wavelength for metallic surface is:

(a) 5$\lambda$                (b)$\frac{5}{2}$$\lambda$

(c) 3$\lambda$                (d) 4$\lambda$

An electron of mass m and a photon have the same energy E. Find the ratio of de-Broglie wavelength associated with the electron to that associated with the photon. (c is the velocity of light)

^{$$\begin{gathered} 1. {\left(\frac{E}{2m}\right)}^{1/2} \\ 2. c{\left(2mE\right)}^{1/2} \\ 3. \frac{1}{c}{\left(\frac{2m}{E}\right)}^{1/2} \\ 4. \frac{1}{c}{\left(\frac{E}{2m}\right)}^{1/2} \end{gathered}$$}
 

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c=velocity of light)

1. E/c

2. 2E/c

3. 2E/c²

4. E/c²

A certain metallic surface is illuminated with monochromatic light of wavelength λ. The stopping potential for photoelectric current for this light is 3V_o. If the same surface is illuminated with light of wavelength 2λ, the stopping potential is V_o. The photoelectric effect's threshold wavelength for this surface is?

1. 6λ

2. 4λ

3. λ/4

4. λ/6