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 $\frac{{\rm{v}}}{4}$. The threshold wavelength for the metallic surface is:

Two protons of emerges twice and thrice the work function of a metal are incident on the metal surface. Then the ratio of maximum velocities of the photoelectrons emitted in the two cases respectively, is

Light of frequency $4{v_0}$ is incident on the metal of the threshold frequency ${v_0}.$ The maximum kinetic energy of the emitted photoelectrons is

Which one of the following statement is wrong in the context of X-rays generated from X-ray tube?

Photons of $5.5\;eV$ energy falls on the surface of the metal emitting photoelectrons of maximum kinetic energy $4.0\;eV.$ The stopping voltage required for these electrons are

The stopping potential $\left( {{V_0}} \right)$

A radio transmitter operates at a frequency of $880\;kHz$ and a power of $10\;kW.$ The number of photons emitted per second are

In Thomson’s mass spectrographs, when an electric field of $2 imes {10^4}\;{\rm{V}}{{\rm{m}}^{ - 1}}$ is applied then the deflection produced on the screen is 20 mm. If the length of the plates is 5 cm and the distance of the screen from plates is 21cm and the velocity of positive ions is ${10^6}{\rm{m}}{{\rm{s}}^{ - 1}}$, then their specific charge will be

The number of photons of wavelength $540\;nm$ emitted per second by an electric bulb of power $100\;W$ is (taking $h = 6 imes {10^{ - 34}}J$-s)

An electron initially at rest, is accelerated through a potential difference of $200\;volt,$ so that it acquires a velocity $8.4 imes {10^6}m/s.$ The value of $e/m$ of electron will be

Light of wavelength $4000\mathop A\limits^ \circ$ is incident on a metal surface. The maximum kinetic energy of emitted photoelectron is 2 eV. What is the work function of the metal surface ?