Chapter 21, Problem 98A

a.

To determine

To Write:A problem which can be solved using electric field for point charge $q=4\text{mC}$ at rest.

Explanation of Solution

Introduction:

Electric field: It is a three-dimensional space around a charge where another charge can experience a force.

Mathematically, Electric field is given as,

  $E=\frac{F}{q}$

Where, $F$ is force experienced by charge and $q$ is point charge.

The question can vary with different data.

One of the problem can be, “A point charge of is at rest. If an electrostatic force of 4N acts on the charge. Find the electric field.”

So,

  $E=\frac{F}{q}=\frac{4}{4\times {10}^{-3}}=1000\text{N/C}$

Here infinite number of questions are possible by changing the electrostatic force value.

b.

To determine

To Write:A problem which can be solved using electric potential for a point charge $q=4\text{mC}$ at rest.

Explanation of Solution

Introduction:

Electric potential: It is the potential energy of a point charge at a given point.

Mathematically, Electric potential is given as,

  $V=\frac{kq}{r}$

Where, $q$ is point charge, $r$ is distance from charge and $k$ is constant.

The question can vary with different data.

One of the problems can be, “A point charge of $q=4\text{mC}$ is at rest. Find the electric potential at a point 4 m away from the point charge.”

So,

  $\begin{array}{c}V=\frac{kq}{r}\\ =\frac{9\times {10}^9\times 4\times {10}^{-3}}{4}\\ =9\text{MV}\end{array}$

Here infinite number of questions are possible by changing thevalue of $r$ .