Embibe Experts Solutions for Chapter: Modern Physics, Exercise 1: Exercise 1

Ultraviolet light of wavelength $66.26 \mathrm{nm}$ and intensity $2 \mathrm{W} {\mathrm{m}}^{-2}$ falls on potassium surface by which photo electrons are ejected. If only $0.1\%$ of the incident photons produce photo electrons, and surface area of metal surface is $4{ \mathrm{m}}^2$, how many electrons are emitted per second?

Thickness of the foil of gold used in $\alpha$-particle scattering experiment is

The scattering $\alpha$-particles were observed through a rotatable detector consisting of a screen of

In Rutherford's experiment, scattering of more than $1°$ was observed in

Energy of the beam of $\alpha$-particles used by Geiger and Marsden in scattering experiment is

An $\mathrm{\alpha }$-particle colliding with one of the electrons in a gold atom loses

The masses of neutron and proton are $1.0087 \mathrm{amu}$ and $1.0073 \mathrm{amu}$ respectively. If a helium nucleus (alpha particles) of mass $4.0015 \mathrm{amu}$ is formed by combining neutrons and protons. The binding energy of the helium nucleus will be $\left(1 \mathrm{amu}=931 \mathrm{MeV}\right)$

The half-life of${}_{92}^{238}\mathrm{U}$ undergoing $\alpha -$ decay is $4.5\times {10}^9$ $\mathrm{years}$. Calculate the activity of $1 \mathrm{g}$ sample of${}_{92}^{238}\mathrm{U}$. (Avogadro's number is $6.022\times {10}^{23}$)