Three identical positive point charges, as shown, are placed at the vertices of an isosceles right-angled triangle. Which of the numbered vectors coincides in direction with the electric field at the mid-point $M$of the hypotenuse?

 

 

An electron is projected, as shown in the figure, with kinetic energy $K$ and at an angle $\text{θ}=45°$ between the two charged plates. What should be the magnitude of the electric field between the plates so that the electron just fails to strike the upper charged plate?

Two concentric rings, one of radius $a$and the other of radius $b$, have the charges $+q$and $-{\left(\frac{2}{5}\right)}^{-\frac{3}{2}}q$, respectively, as shown in the figure.

Find the ratio $\frac{b}{a}$ if a charged particle placed on the axis at $z=a$is in equilibrium.

A charge $(-q, m)$ is projected with an initial velocity $v_0$ in the direction of a unidirectional field $E_{0}x$ as shown in the figure. Find the distance covered by the charge before it comes to rest.