The curves (1), (2), (3) and (4) show the variation between the applied potential difference (V) and the photoelectric current (i), at two different intensities of light ( ${\mathrm{I}}_1>{\mathrm{I}}_2$). In which figure is the correct variation shown?

1.		2.
3.		4.

A stationary nucleus of mass number A emits an \(\alpha-\text{particle}\).  If the de-Broglie wavelength of the daughter nucleus is ${\lambda }_1$ and that of the $\mathrm{\alpha }$-particle is ${\lambda }_2$, then the ratio $\frac{{\lambda }_1}{{\lambda }_2}$ is:

1.  $\frac{4}{A - 4}$

2.  $\frac{A - 4}{4}$

3.  1

4.  $\frac{A + 4}{4}$

In the Davisson and Germer experiment, how can we increase the velocity of electrons emitted from the electron gun?

When monochromatic photons of wavelength 4000 Å are incident on the metal plate of work function 2.1 eV, what will be the stopping potential for the photocurrent?

1.  1 V

2.  2.1 V

3.  3.1 V

4.  Zero

The stopping potential of a photosensitive material is \(4~V\) when the wavelength of incident monochromatic radiation is $$\(\lambda.\) If the wavelength of incident radiation is doubled on the same photosensitive material, the stopping potential becomes \(V.\) The threshold wavelength of the photosensitive material will be:

1.  $\frac{4}{3}\lambda$

2.  $\frac{3}{2}\lambda$

3.  $3\lambda$

4.  $\frac{\lambda }{4}$

A metallic surface is exposed to two radiations separately, one of wavelength 4000 Å and the other of 8000 Å. If the work function of metal is 1 eV, then the ratio of maximum kinetic energies of photoelectrons is nearly equal to:

1.  $\frac{32}{11}$

2.  $\frac{42}{11}$

3.  $\frac{52}{11}$

4.  $\frac{62}{11}$

The figure shows the variation in photoelectric current (i) with voltage (V) between the electrodes in a photocell for two different radiations. If I_a and I_b are the intensities of the incident radiation and ${\mathrm{\nu }}_{\mathrm{a}}$ and ${\mathrm{\nu }}_{\mathrm{b}}$ their respective frequencies, then:

1.  $I_a > I_b , {\nu }_b < {\nu }_a$

2.  $I_a < I_b , {\nu }_b > {\nu }_a$

3.  $I_a > I_b , {\nu }_b = {\nu }_a$

4.  $I_a < I_b , {\nu }_b < {\nu }_a$

The work function of a metal surface is 2 eV. When the light of frequency f is incident on the surface, the maximum kinetic energy of the photoelectrons emitted is 5 eV. If the frequency of the incident light is increased to 4f, then the maximum kinetic energy of the photoelectron emitted will be:

1.  20 eV

2.  22  eV

3.  26 eV

4.  28 eV

When a point source of monochromatic light is at a distance of 0.2 m from a photoelectric cell, the cut-off voltage and saturation current are 0.6 volts and 18 mA respectively. What will happen if the same source is placed 0.6 m away from the photoelectric cell?

1.  the stopping potential will be 0.2 volts.

2.  the stopping potential will be 0.6 volts.

3.  the saturation current will be 6 mA.

4.  the saturation current will be 18 mA.

The de-Broglie wavelength of an electron is the same as that of a photon of wavelength λ . If the mass of an electron is m, then its kinetic energy will be:

1.  $\frac{h^{2}m}{2{\lambda }^2}$

2.  $\frac{2h{m}^2}{{\lambda }^2}$

3.  $\frac{h^2{\lambda }^2}{2m}$

4.  $\frac{h^2}{2m{\lambda }^2}$