Question

Why are alpha-particle tracks observed in a cloud chamber much shorter than beta-particle tracks, though both are emitted from the same radioactive sample and have almost the same speed?

Answer 1

Alpha-particle tracks are much shorter because α-particles are heavier and carry a greater charge than β-particles. Therefore, they produce stronger ionisation and lose their energy more rapidly while passing through the cloud.

Hence, α-particles have a shorter range than β-particles, even though their speeds are nearly the same.