An electron beam passes through a magnetic field of `2xx10^(-3)` T and electric field of `3xx10^(-4)` V/m at right angles to it. Its specific charge is `1.75xx10^(11)C//kg^(-1)`. What is the radius of the path in which it is deflected, if there is no deflection, when both fields are acting ?

Options

A. 0.43 m
B. 4.3 cm
C. 0.43 cm
D. none of the above.

Answer

B

Explanation

`v=(E)/(B)=(3xx10^(4))/(2xx10^(-3))=1*5xx10^(7) ms^(-1)`
Also `BeV=(mv^(2))/(r) or v=(Ber)/(m)`
or `r=(mv)/(Be)=(1.5xx10^(7))/(2xx10^(-3)xx1*75xx10^(11))`
`=(1500)/(200)xx(1)/(175)=(15)/(350)xx100 cm=(30)/(7) cm=4*3 cm`