Embibe Experts Solutions for Chapter: Electrons and Photons, Exercise 1: Exercise 1

In photoelectric effect,

Which one of the following metals is used in the filaments of photoelectric cells that convert light energy into electric energy?

In photoelectric effect, to eject four photoelectrons, minimum number of photons required is

A pulse of light of duration $100 \mathrm{ns}$ is absorbed completely by a small object initially at rest. Power of the pulse is $30 \mathrm{mV}$ and the speed of light is $3\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$. The final momentum of the object is

Momentum of $\gamma$ ray photon of energy $3 \mathrm{keV}$ in $\mathrm{kg}-{\mathrm{ms}}^{-1}$ will be

The curve drawn between velocity and frequency of photon in vacuum will be a

An impulse laser may be treated as a source of photons that are emitted during the time interval of the pulse which is followed by a time interval when no photons are produced. Pulses are periodically repeated. A laser beam of diameter $d=10$ microns is directed upward and is perpendicular to the thin foil surface which has an index of reflection $\rho =0.50$ (see the sketch of the experiment). The index of reflection of the surface is the ratio of the reflected energy to the impact energy. A pulse with duration of $0.13 \mathrm{ms}$ has a total energy of $10 \mathrm{J}$. What is the mass of the piece of foil that can be supported in the air solely by the light pressure of the laser beam?

A particle having zero rest mass and non-zero energy and momentum must travel with a speed