In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

1. increasing the filament current

2. decreasing the filament current

3. decreasing the potential difference between the anode and filament

4. increasing the potential difference  between the anode and filament

A radioactive nucleus of mass M emits a photon

of frequency $\nu$ and the nucleus recoils. The recoil

energy will be:

(1) ${\mathrm{h}}^2{\mathrm{\nu }}^2/2 {\mathrm{Mc}}^2$

(2) zero

(3) h$\nu$

(4) ${\mathrm{Mc}}^2-\mathrm{h\nu }$

Photoelectric emission occurs only when the incident light has more than a certain minimum 

1. wavelength

2. intensity

3. frequency

4. power

The threshold frequency for a photo-sensitive metal is $3.3\times {10}^{14} \mathrm{Hz}.$ If the light of frequency $8.2\times {10}^{14} \mathrm{Hz}$ is incident on this metal, the cut-off voltage for the photo-electric emission is nearly:

1. 2 V                                        2. 3 V

3. 5 V                                         4. 1 V

The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three difference radiations. Which one of the following is a correct statement?

(1) Curves a and b represent incident radiations of different frequencies and different intensities

(2) Curves a and b represent incident radiations of same frequency but of different intensities 

(3) Curves b and c represent incident radiations of different frequencies and different intensities

(4) Curves b and c represent incident radiations of same frequency having same intensity 

An electron $\left(mass m\right)$ with an initial velocity v=${\mathrm{v}}_0\hat{\mathrm{i}} \left({\mathrm{v}}_0>0\right)$ is in an electric field E$=-E_0 \hat{i}\left(E_0=cons\tan t > 0\right).$ It's de Broglie wavelength at the time $t$ is given by:

(1) $\frac{{\lambda }_0}{\left(1+{\displaystyle \frac{e{E}_0}{m}}{\displaystyle \frac{t}{v_0}}\right)}$

(2) ${\lambda }_0\left(1+\frac{e{E}_{0}t}{m{v}_0}\right)$

(3) ${\lambda }_0$

(4)${\lambda }_{0}t.$

Cathode rays are similar to visible light rays in that

(1) They both can be deflected by electric and magnetic fields

(2) They both have a definite magnitude of wavelength

(3) They both can ionize a gas through which they pass

(4) They both can expose a photographic plate