Question

An electron, proton, deuteron and a-particle enter in a uniform electric field with the same velocity as shown. The greatest deviation is shown by

• A. electron
• B. proton
• C. deuteron
• D. $\alpha$ -particle

Answer 1

Answer: (A)

Since all of them have the same velocity, they will take the same time to cross over. Let it be $t$
$a=\frac{qE}{m}y=\frac{1}{2}a{t}^2=\frac{1}{2}\left(\frac{qE}{m}\right)t^2$
The deviation will be greatest for the one with greatest $q/m$ ratio. Here it is electron as its mass is very small compared to others