Question

A beam of $\alpha$ particles having specific charge $2.5\times10^7\,C\,kg^{-1}$ moves with a speed of $2\times10^5\,ms^{-1}$ in a magnetic field of $0.05\, T$. The radius of the circular path described by the $\alpha$-particle is

• A. 4 cm
• B. 8 cm
• C. 16 cm
• D. 32 c

Answer 1

Answer: (C)

16 cm

Answer 2

R = $\frac{M \, v}{B_{q0}} = \frac{v}{B} ( \frac{q_0}{M})$ $= 2 \times 10^5 / 0.05 \times 2.5 \times 10^7$ = 0.16 m = 16 cm.