Question

The tracks of three charged particles in a uniform electrostatic field are shown in the figure. Which particle has the highest charge to mass ratio?

• A. $A$
• B. $B$
• C. $C$
• D. $A$ and $B$

Answer 1

Answer: (C)

Particles $A$ and $B$ have negative charges because they are being deflected towards the positive plate of the electrostatic field. Particle $C$ has positive charge because it is being deflected towards the negative plate.
$\therefore $ Deflection of charged particle in time $t$ in $y$-direction
$h=0\times t+\frac{1}{2}at^{2}=\frac{1}{2} \frac{qE}{m}t^{2}$ i.e. $h\propto q /m$
As the particle C suffers maximum deflection in y-direction, so it has highest charge to mass $q/m$ ratio.