Question

$\alpha ,\beta$ and $\gamma$-rays emitted from a radioactive source are passed through a $0.5cm$ thick aluminium sheet. The out going radiations will consist of

• A. $\alpha ,\beta$ and $\gamma$-rays
• B. $\gamma$ and $\beta$-rays only
• C. $\gamma$ rays only
• D. $\alpha$ rays only

Answer 1

The correct option is B $\gamma$ and $\beta$-rays only

The penetrating power of alpha rays, beta rays, and gamma rays varies greatly. Alpha particles can be blocked by a few pieces of paper. Beta particles pass through paper but are stopped by aluminium foil. Gamma rays are the most difficult to stop and require concrete, lead, or other heavy shielding to block them.

So, alpha particles are stopped by aluminium sheet and only beta and gamma emerges other side.