Question

A uniform electric field of $10 N / C$ is created between two parallel charged plates (as shown in figure) An electron enters the field symmetrically between the plates with a kinetic energy $05 eV$ The length of each plate is $10 cm$ The angle $(\theta)$ of deviation of the path of electron as it comes out of the field is ___ (in degree)

Answer 1

The correct answer is 45
0.5e $=\frac{1}{2}\ mv^{2}_x$ ⇒ vx $=\sqrt{\frac{e}{m}}$
Along x L = vxt $=\sqrt{\frac{e}{m}t}$
Along y vy = $\frac{eE}{m}t$
dividing $\frac{v_y}{L}=E\sqrt{\frac{e}{m}}=Ev_x$
⇒ Tan $\theta=\frac{v_y}{v_x}=E\times L=10\times0.1=1$
$\theta=45°$