Question

Complete the following: __________ radiation deviates minimum in a magnetic field.

• A. Alpha
• B. Beta

Hint:

Think of it like throwing a bowling ball (Alpha) and a ping-pong ball (Beta) through a strong cross-wind (magnetic field). The much heavier bowling ball will deviate far less.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept: The deflection of charged particles in a magnetic field is governed by the Lorentz force and the particle's inertia (mass).
Step 2: Key Formula or Approach: The radius of curvature \( r \) for a particle of mass \( m \), charge \( q \), and velocity \( v \) in a magnetic field \( B \) is:
\[ r = \frac{mv}{qB} \]
Smaller deflection (deviation) corresponds to a larger radius of curvature.
Step 3: Detailed Explanation: - Alpha (\( \alpha \)) particles are helium nuclei with a mass of approximately \( 4\text{ u} \) and a charge of \( +2\text{e} \).
- Beta (\( \beta \)) particles are fast-moving electrons with a mass of approximately \( \frac{1}{1840}\text{ u} \) and a charge of \( -1\text{e} \).
For similar velocities, the mass-to-charge ratio (\( m/q \)) for an alpha particle (\( 4/2 = 2 \)) is much larger than that for a beta particle (\( \approx 0.0005 \)).
Because alpha particles have much greater mass (inertia), they are harder to deflect, resulting in minimum deviation compared to beta particles.
Step 4: Final Answer: Alpha radiation deviates minimum.