A ring of the radius $R$ has charge $Q$ distributed uniformly over it. Calculate the charge that should be placed at the centre of the ring such that the electric field becomes zero at a point on the axis of the ring at distance $R$ from the centre of the ring.

Is an electric field of the type shown by the electric lines in the figure physically possible?

Figure shows three electric field lines.

At which point, $\mathrm{A}$ or $\mathrm{B}$, will the acceleration of the test charge be greater if the charge is released?

Figure shows that $E$ has the same value for all points in front of an infinitely charged sheet. Is this reasonable? One might think that the field should be stronger near the sheet, because the charges are so much closer

Figure shows the tracks of three charged particles in a uniform electrostatic field projected parallel to a plate with the same velocity. Give the signs of the three charges. Which of the three particles has the highest charge to mass ratio?

Two charged metal plates in vacuum are $10 \mathrm{c}\mathrm{m}$ apart. A uniform electric field of intensity $\left(\frac{45}{16}\right)\times {10}^3 \mathrm{N} {\mathrm{C}}^{-1}$ is applied between the plates. An electron is released between the plates from rest at a point just outside the negative plate.

(a) Calculate how long $\left(t\right)$ will the electron take to reach the other plate.

(b) At what velocity $\left(v\right)$ will it be going just before it hits the other plate?

An electron moving in a gravitational free space enters a uniform electric field $E$ with an initial velocity $v_0$ as shown in the figure.

$\left(\mathrm{a}\right)$ Find the deflection distance undefined in the field.

$\left(\mathrm{b}\right)$ Find an expression for the velocity of the electron when it just emerges from the field.

$\left(\mathrm{c}\right)$ Find an expression for the total deflection distance $H$ at a vertical screen placed at a distance $l$ from the region of the uniform field. (Assume that the field abruptly ends outside the field.)