What uniform magnetic enter a magnetic field applied perpendicular to a beam of electrons moving at `1.3xx10^(6) ms^(-1)` is required to make the electrons travel in a circular arc of radius 0.35 m

Options

A. `21 xx10^(-5) T`
B. `6xx10^(-5)T`
C. `2.1 xx 10^(-5)T`
D. `6xx10^(-5)T`

Answer

C

Explanation

Radius `r=(mv)/(qB)`
or magnetic due to moving electron `B=(mv)/(qr)`
`=(9.1xx10^(-31)xx1.3xx10^(6))/(1.6xx10^(-19)xx0.35)=2.1xx10^(-5)T`