Question

An electron has mass $9\times {10}^{-31}kg$ and charge $1.6\times {10}^{-19}C$ is moving with a velocity if ${10}^{6}m/s,$ enters a region where magnetic field exists. If it describes a circle of radius $0.10m$, the intensity of magnetic field must be:

• A. $1.8\times {10}^{-4}T$
• B. $5.6\times {10}^{-5}T$
• C. $14.4\times {10}^{-5}T$
• D. $1.3\times {10}^{-6}T$

Answer 1

Answer: (A)

$1.8\times {10}^{-4}T$

Given:-

Electron = $9\times {10}^{-31}kg$

Charge = $1.6\times {10}^{-19}C$

Velocity = ${10}^{6}m/s$

Radius of circle = $0.1m$

$R=\frac{mv}{qB}$

$B=\frac{mv}{qR}=\frac{9\times {10}^{-31}\times {10}^6}{1.6\times {10}^{-19}\times 0.1}=5.6\times {10}^{-5}T$