Question

A proton takes ${10}^{-12}$ seconds to complete one revolution in uniform magnetic field. The time taken in another orbit of double the radius in the same field is

• A. $0.5\times {10}^{-12}$seconds
• B. $2\times {10}^{-12}$ seconds
• C. $4\times {10}^{-12}$ seconds
• D. ${10}^{-12}$ seconds

Answer 1

Answer: (D)

${10}^{-12}$ seconds

Time period of charged particle in uniform magnetic field is given by $T=\frac{2\pi m}{qB}$
Times period does not depends on radius.
So $T$ will remain same.