Embibe Experts Solutions for Chapter: Dual Nature of Matter and Radiation, Exercise 2: Exercise-2

If $\lambda ={10}^{-10} \mathrm{m}$ changes to ${\lambda }^{\text{'}}=0.5\times {10}^{-10} \mathrm{m}$, find energy difference $\left(\mathrm{\Delta }E\right)$ given to the particle

In Davisson-Germer experiment when electron strikes the $Ni$-crystal which of the following is produced?

The anode voltage of photocell is kept fixed. The wavelength $\left(\lambda \right)$ of the light falling on the cathode is gradually changed. The maximum kinetic energy $(\mathrm{K}.\mathrm{E}.)$ of the photoelectrons emitted varies with $\lambda$ as

Assertion : Work function of aluminium is $4.2eV\mathit{.}$ Emission of electrons will not be possible if two photons each of energy $2.5eV$ collide with free electrons of aluminium.

Reason : For photoelectric emission the energy of each photon should be greater than or equal to the work function of aluminium.

Assertion : Photoelectric effect demonstrates the wave nature of light.

Reason : The number of photoelectrons is proportional to the frequency of light.

Assertion : $X$-rays travel with the speed of light.

Reason : $X$-rays are electromagnetic rays.

Assertion : Kinetic energy of photo electrons emitted by a photosensitive surface depends upon the inten sity of incident photon.

Reason : The ejection of electrons from metallic surface is possible with frequency of incident photon below the threshold frequency. 

Assertion: Photosensitivity of metal is high f its work function is small.
Reason: Work function $=h{f}_0$ where $f_0$ is the threshold frequency.