Question

A proton and an alpha-particle enter a uniform magnetic field with the same velocity. The period of rotation of the alpha particle will be –

• A. Four times that of the proton
• B. Two times that of the proton
• C. Three times that of the proton
• D. Same as that of the proton

Answer 1

Answer: (B)

Two times that of the proton

Answer 2

T = $\frac{2\pi m}{Bq}$; Tµ$\frac{m}{q}$ Ž $\frac{T_{\alpha}}{T_{p}} = \frac{m_{\alpha}}{q_{\alpha}} \times \frac{q_{p}}{m_{p}} = \frac{4}{2} = \frac{2}{1}$

T_a = 2T_p