Question

A cathode ray beam is bent in a circle of radius 2 cm by a magnetic induction $4.5\times {10}^{-3}weber/m^2$. The velocity of electron is

• A. $3.43\times {10}^{7}m/s$
• B. $5.37\times {10}^{7}m/s$
• C. $1.23\times {10}^{7}m/s$
• D. $1.58\times {10}^{7}m/s$

Answer 1

The correct option is D $1.58\times {10}^{7}m/s$

$v=\frac{Bqr}{m}$
$=\frac{4.5\times {10}^{-3}\times 1.6\times {10}^{-19}\times 2\times {10}^{-2}}{9.1\times {10}^{-32}}$

$=1.58\times {10}^{7}m/s$