Question

An electron is moving in a perpendicular magnetic field of strength $4\times {10}^{-3}T$ with a velocity of $4\times {10}^{7}m/s$. The radius of electron path will be

• A. $0.56m$
• B. $0.056m$
• C. $56m$
• D. $5.6m$

Answer 1

The correct option is B $0.056m$

Radius of the circular orbit $r=\frac{mv}{qB}=\frac{4\times {10}^7}{1.76\times {10}^{11}\times 4\times {10}^{-3}}=0.056m$
We have sued $\frac{e}{m}=1.76\times {10}^{11}C/kg$