Question

A velocity selector consists of electric and magnetic fields described by the expressions e with arrow = e k and b with arrow = b ĵ, with b = 22.0 mt. find the value of e such that a 850-ev electron moving in the negative x direction is undeflected.

Answer 1

Answer:

380.38 kV/m

Explanation:

We are given that

$Electric field=E$

Magnetic field,B=22 mT=$22\times 10^{-3} T$

$1mT=10^{-3} T$

K.E=850e V=$850\times 1.6\times 10^{-19} J$

Charge on electron,q=$1.6\times 10^{-19} C$

Mass of electron,m=$9.1\times 10^{-31} kg$

Speed of electron,v=$\sqrt{\frac{2K.E}{m}$

$v=\sqrt{\frac{2\times 850\times 1.6\times 10^{-19}}{9.1\times 10^{-31}}}$

$v=17.29\times 10^6 m/s$

$E=vB=17.29\times 10^6\times 22\times 10^{-3}=380.38\times 10^3 V/m=380.38KV/m$

1 kV=$10^3 V$