A $+8.75$-mC point charge is glued down on a horizontal frictionless table. It is tied to a $-6.50$-mC point charge by a light, nonconducting $2.50$-cm wire. A uniform electric field of magnitude $1.85\times {10}^8$ $N/C$ is directed parallel to the wire, as shown in Fig. E$21.34$. Find the tension in the wire.

A uniform electric field exists in the region between two oppositely charged plane parallel plates. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate, $1.60$ cm distant from the first, in a time interval of $3.20\times {10}^{-6}$ s. Find the magnitude of the electric field.

Two positive point charges $q$ are placed on the $x$-axis, one at $x = a$ and one at $x = -a$. Derive an expression for the electric field at points on the $x$-axis. Use your result to graph the $x$-component of the electric field as a function of $x$, for values of $x$ between $-4a$ and $+4a$.

A uniform electric field exists in the region between two oppositely charged plane parallel plates. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate, $1.60$ cm distant from the first, in a time interval of $3.20\(\times\)10^{-6}$ s. Find the speed of the proton when it strikes the negatively charged plate.

Calculate the magnitude and direction (relative to the $+x$-axis) of the electric field in Example $21.6$. Example $21.6$: A point charge $q=-8.0$ nC is located at the origin. Find the electric-field vector at the field point $x=1.2$ m, $y=-1.6$ m.

A $+8.75$-mC point charge is glued down on a horizontal frictionless table. It is tied to a $-6.50$-mC point charge by a light, nonconducting $2.50$-cm wire. A uniform electric field of magnitude $1.85\(\times\)10^8$ $N/C$ is directed parallel to the wire, as shown in Fig. E$21.34$. What would the tension be if both charges were negative?

Two positive point charges $q$ are placed on the $x$-axis, one at $x=a$ and one at $x=-a$. Find the magnitude and direction of the electric field at $x=0$.