Light of frequency $1.8

u_0$(where$

u_0$is the threshold frequency) is incident on a metal surface. If the intensity is quadrupled and the frequency is changed to$0.9

u_0$, what will be the observed photocurrent?

When monochromatic radiation of intensity $I$ falls on a metal surface, the number of photoelectron and their maximum kinetic energy are $N$ and $T$ respectively. If the intensity of radiation is $2I,$ the number of emitted electrons and their maximum kinetic energy are respectively

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

Air becomes conducting when the pressure ranges between

The colour of the positive column in a gas discharge tube depends on

The energy of a photon of light with wavelength $5000\;\mathop A\limits^ \circ$ is approximately $2.5\;eV.$ This way the energy of an $X$-ray photon with wavelength $1\mathop A\limits^ \circ$would be

If the work function of a photometal is $6.825\;eV.$ Its threshold wavelength will be $\left( {c = 3 imes {{10}^8}\;m/s} \right)$

In a discharge tube ionization of enclosed gas is produced due to collisions between

An ionisation chamber, with parallel conducting plates as anode and cathodes has $5 imes {10^7}{\rm{\;c}}{{\rm{m}}^{ - 3}}$ electrons and the same number of singly charged positive ions per ${\rm{c}}{{\rm{m}}^3}$. The electrons are moving toward the anode with velocity 0.4${\rm{m}}{{\rm{s}}^{ - 1}}$. The current density from anode to cathode is $4{\rm{\mu A}}{{\rm{m}}^{ - 2}}.$ The velocity of positive ions moving towards cathode is

Light of frequency ${\rm{1}}{\rm{.5}}$ times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled ?

From the following, what charges can be present on oil drops in Millikan’s experiment

(Here $e$ is the electronic charge)