Embibe Experts Solutions for Chapter: Dual Nature of Matter and Radiation, Exercise 1: KEAM 2018

A monochromatic light of frequency $v=\frac{1}{6.63}\times {10}^{16} \mathrm{Hz}$ is produced by a laser. The power emitted is $P={10}^2 \mathrm{W}.$ The average number of photos per second emitted by the source is

Among the following photosensitive substances, the one which emits electrons when it is illuminated by visible light is

The work function of three photosensitive materials used to build photoelectric devices are given as : Sodium $(2.75 \mathrm{eV}),$ copper $(4.65 \mathrm{eV})$ and gold $(5.1 \mathrm{eV}).$ Which of the following statements is correct. (The frequency of visible light lies in the range $4\times {10}^{14} \mathrm{Hz}$ to $8\times {10}^{14} \mathrm{Hz}) ?$

The radiation produced by a $100 \mathrm{W}$ bulb has the following property

An electromagnetic wave of intensity $I$ is incident on a non-reflecting surface. If $C$ is the speed of light in free space, then the ratio $\frac{I}{C}$ is same as

The de Broglie wavelength of the matter wave associated with an object dropped from a height $\mathrm{x}$, when it reaches the ground-is proportional to

The mean momentum of a nucleon inside a nucleus with mass number $A$ varies as

Two electrons in two hydrogen-like atoms $A$ and $B$ have their total energies $E_A$ and $E_B$ in the ratio $E_A:E_B=1 :2$ . Their potential energies $U_A$ and $U_B$ are in the ratio $U_A :U_B=1 :2$ . If ${\lambda }_A$ and ${\lambda }_B$ are their de-Broglie wavelengths, then ${\lambda }_A :{\lambda }_B$ is