Embibe Experts Solutions for Exercise 3: Assignment Set-2

The wavelength of photon of energy$E$ is same as the de Broglie wavelength of a material particle moving with the $7.5\times {10}^7{ \mathrm{ms}}^{-1}$ and kinetic energy $E^{\text{'}}$. Then $\frac{E}{E^{\text{'}}}$ is

A silver ball of radius $4.8 \mathrm{cm}$ is suspended by a thread in the vacuum chamber. UV light of wavelength $200 \mathrm{nm}$ is incident on the ball for some times during which a total energy of $1\times {10}^{-7} \mathrm{J}$ falls on the surface. Assuming on an average one out of ${10}^3$ photons incident is able to eject electron. The potential on sphere will be $n\vee$. Value of $n$ rounded off to integer, is

Photons are incident from vacuum on a transparent material with a refractive index $1.50$ for a given wavelength. The momentum of the incident photon, if its wavelength in the material is equal to$\lambda$, is $\frac{h}{n\lambda }$. Value of$n$, is

Energy from the sun is received on the earth at the rate of $2\mathrm{cal}/{\mathrm{cm}}^2/\min$. If average wavelength of solar light be taken at $5500 \mathrm{\AA }$, then photons received on the face of earth facing the sun in$1$ hour (approx.), is $1.76\times {10}^N$. Value of$N$, is
($1$cal = $4.2 \mathrm{J}$, Radius of earth $=6400 \mathrm{km}$ ).

An electron of mass $m$ when accelerated through a potential difference $V$, has a de Broglie wavelength $\mathrm{\lambda }$. The de Broglie wavelength associated with a proton of mass$M$ accelerated through a potential difference $4 \mathrm{V}$ will be $\frac{\lambda }{n}\sqrt{\frac{m}{M}}$$.$

A beam of light of flux density $30 \mathrm{kW}/{\mathrm{m}}^2$ is incident normally on a $100{ \mathrm{mm}}^2$ completely absorbing screen. If $P$ is the pressure exerted on the screen, then $P={10}^{-n} \mathrm{N}/{\mathrm{m}}^2$. Value of$n$, is

Light of wavelength $2000 \mathrm{\AA }$ falls on a metallic surface whose work function is $4.21 \mathrm{eV}$. Calculate the stopping potential.

When ultraviolet radiation is incident on a surface, no photoelectrons are emitted. It is possible to cause emission by using