List of top Physics Questions on Photoelectric Effect

The kinetic energy of the released electron in photoelectric effect depends on

In photo electric experiment, if the wavelength of incident light on the metal changes from 200 nm to 300 nm. The decrease in stopping potential is about ($\frac{hc}{e} = 1240$ eV - nm)

Photoemission of electrons occurs from a metal (\( \phi_0 = 1.96 \, \text{eV} \)) when light of frequency \( 6.4 \times 10^{14} \, \text{Hz} \) is incident on it. Calculate: Energy of a photon in the incident light, The maximum kinetic energy of the emitted electrons, and The stopping potential.

Assertion : Photoelectric effect is a spontaneous phenomenon. Reason (R): According to the wave picture of radiation, an electron would take hours/days to absorb sufficient energy to overcome the work function and come out from a metal surface.

Light of which of the following colours will have the maximum energy in a photon associated with it?

The work function of a material is $6.6 \text{ eV}$. Then, the threshold wavelength of the metal is approximately (Take $h = 6.6 \times 10^{-34} \text{J.s}$)}

Two light rays of wavelength \(\lambda\) and \(\frac{\lambda}{4}\) incident on the surface of a photo sensitive material emit electrons with max kinetic energy \(E\) and \(6E\) respectively. The work function of the material is (\(h\) = Planck’s constant, \(c\) = velocity of light in free space)

The velocity of the photoelectron (\(in~ms^{-1}\)) emitted when a smooth surface of a metal is made to strike with a photon of wavelength \(4\times10^{-7}m\) (\(W_{0}\) of metal \(=2.13~eV\); \(1eV=1.6\times10^{-19}J\); \(h=6.6\times10^{-34}Js\); \(m_{e}=9.1\times10^{-31}kg\))

Photons of energy 4.2 eV are incident on a photosensitive material of work function 1.7 eV. If the emitted photoelectrons enter normally into a uniform magnetic field of \(\sqrt{2}\times10^{-4}T\), then the largest radius of the circular path described by the photoelectrons is nearly

The work function of a metal is \(4.0\text{ eV}\). If the metal is irradiated with radiation of wavelength \(200\text{ nm}\), the maximum kinetic energy of the photoelectrons would be about:
(Use \(hc = 1240\text{ eV}\cdot\text{nm}\))

When photons of wavelength $4000\text{ \AA}$ are incident on a photosensitive material of cut-off wavelength $4800\text{ \AA}$, the stopping potential is $V$. If the same photons are incident on another photosensitive material of cut-off wavelength $6000\text{ \AA}$, then the stopping potential is:

Monochromatic light of frequency \( 8 \times 10^{14} \, \text{Hz} \) is incident on a metal surface whose threshold frequency is \( 5 \times 10^{14} \, \text{Hz} \). The stopping potential is approximately:
(Given \( h = 6.6 \times 10^{-34} \, \text{J s} \), \( e = 1.6 \times 10^{-19} \, \text{C} \))

The energy of a photon of wavelength 2500 is 4.96 eV. When photons of wavelength 3100 incident on a photosensitive material of work function 2.2 eV, the maximum velocity of the emitted photoelectrons is:

The threshold frequency for a certain photosensitive metal surface is _0. When light of frequency 2_0 is incident on the surface, the maximum velocity of the emitted photoelectrons is v_1. If the frequency is increased to 5_0, the maximum velocity becomes v_2. The ratio v_1 : v_2 is:

In a photoelectric experiment, the stopping potential for incident light of wavelength \(4000\ \text{\AA}\) is \(2\ \text{V}\). If the wavelength is changed to \(3000\ \text{\AA}\), the new stopping potential will be approximately \[ (\text{Use }h=4.14\times 10^{-15}\ \text{eV s},\ c=3\times 10^8\ \text{m/s}) \]

Radiation of wavelength \( \lambda \) is incident on a photocell. The fastest emitted electron has speed \( v \). If the wavelength is changed to \( \frac{3\lambda}{4} \), then the speed of the fastest emitted electron will be

Work function of the metal is

Pick out the WRONG statements about magnetic substances (\(\chi\) = magnetic susceptibility) (\(\mu_r\) = relative permeability).
I. Substances with \(-1 \le \chi<0\) are diamagnetic
II. Substances with \(\chi \gg 1\) are paramagnetic
III. Substances with \(\chi \ll 1\) are ferromagnetic
IV. Substances with \(\mu_r \gg 1\) are ferromagnetic

If the energy of the incident radiation on a metal is increased by $10%$, the kinetic energy of the emitted photoelectrons increases from $0.5,eV$ to $0.75,eV$, then the work function of the metal is

The work functions of two metals are 2.75 eV and 2 eV respectively. If these are irradiated by photons of energy 3 eV, the ratio of maximum momenta of the photoelectrons emitted respectively by them is

The work function for a metal having threshold frequency $5\times 10^7\text{ Hz}$ is?

Determine the energy of a photon in eV if its wavelength is \( 4000\ \text{\AA} \).

Light is incident on a metallic plate having work function \(110 \times 10^{-20}\,\text{J}\). If the produced photoelectrons have zero kinetic energy, then the angular frequency of the incident light is _________ rad/s. (\(h = 6.63 \times 10^{-34}\,\text{J·s}\))}

When a light of a given wavelength falls on a metallic surface the stopping potential for photoelectrons is \(3.2\ \text{V}\). If a second light having wavelength twice of the first light is used, the stopping potential drops to \(0.7\ \text{V}\). The wavelength of the first light is ________ m.