Question

An electron c penetrates through a thin plate A and enters the electric field region between parallel plates A and B. It gets slowed down Three other particles-proton (p), alpha particles $(\alpha )$ and beta particles $({\beta }^{-})$ - similarly penetrate through either plate A or plate B as shown. The correct statement as regards the speed of the particles is

• A. only speed of p increases
• B. speeds of both $\alpha$ and $\beta -$ increases
• C. speeds of both $p$ and $\beta -$ increases
• D. speed of only $\alpha$ increases

Answer 1

Answer: (C)

Here electric field between plates A and B is directed from A to B.
Proton has positive charge and is moving along direction of electric field, hence its speed increases.
$\beta$ has negative charge and is moving opposite to the direction of electric field, hence its speed increases.