Question

A proton and an α-particle, accelerated through the same potential difference, enter a region of uniform magnetic field normally. If the radius of the proton orbit is 10 cm, then the radius of α-particles is?

• A. 10 cm
• B. 20 cm
• C. \( \sqrt{2} \) cm
• D. 5 cm

Hint:

For charged particles in a magnetic field, the radius of the orbit depends on the charge and mass of the particle.

Answer 1

The Correct Option is B

The radius of the orbit of a charged particle in a magnetic field is proportional to the mass and the charge of the particle. Since the α-particle has twice the charge and four times the mass of a proton, its radius will be greater by a factor of 2.