Question

An electron enters in a magnetic field of intensity 5T with a velocity $2\times {10}^{7}m/s$ in a direction perpendicular to the field. Calculate the force on the electron.[charge on electron is $-1.6\times {10}^{-19}C$]

• A. $2.0\times {10}^{-10}T$
• B. $1.6\times {10}^{-11}T$
• C. $2.5\times {10}^{-8}T$
• D. $0.4\times {10}^{-11}T$

Answer 1

The correct option is B $1.6\times {10}^{-11}T$

Magnitude of the force on the electron: $F=qvBsin\theta$
$=1.6\times {10}^{-19}\times 2\times {10}^7\times 5\times sin{90}^0$
$=1.6\times 10\times {10}^{-19}\times {10}^7\times 1$
$=1.6\times {10}^{-11}N$