An electron has mass `9xx10^(-31)kg` and change `1.6xx10^(-19)C` is moving with a velocity of `10^(6)m//s`, enters a region where magnetic field exists. If it describes a circle of radius `0.10m`, the intensity of magnetic field must be

Options

A. `1.8 xx 10^(-4) T`
B. `5.6 xx 10^(-5) T`
C. `14.4 xx 10^(-6) T`
D. `1.3 xx 10^(-6) T`

Answer

B

Explanation

`r = (mv)/(qB) = (9 xx 10^(-31) xx 10^(6))/(1.6 xx 10^(-19) xx B)`
`implies B = (9 xx 10^(-31) xx 10^(6))/(1.6 xx 10^(-19) xx 0.1) = 5.6 xx 10^(-5) T`