Practice Electric Field in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Worksheet PDF Free Answer-key PDF Family

Quick Recap

A region around a charged object where other charges experience a force. Measured in newtons per coulomb (N/C) or volts per meter (V/m).

Every charge creates an invisible 'force zone' around it. Another charge entering this zone feels a push or pull without touching anything.

Showing a random 20 of 50 problems.

Example 1

easy
A test charge of 2 C2 \text{ C} feels a force of 10 N10 \text{ N} at a point. What is the electric field there?

Example 2

challenge
On the line joining +9 μC+9\ \mu\text{C} at x=0x=0 and −1 μC-1\ \mu\text{C} at x=2 mx=2\ \text{m}, where does the net field vanish? (Search outside the segment.)

Example 3

medium
Find the field EE at the surface of a sphere of radius 0.10 m0.10\ \text{m} carrying 1.0 μC1.0\ \mu\text{C} of charge. Use k=9×109k = 9\times10^9.

Example 4

medium
Charges +4 C+4 \text{ C} at x=0x=0 and +4 C+4 \text{ C} at x=4 mx=4 \text{ m}. Find the field at x=2 mx=2 \text{ m}.

Example 5

easy
A point charge gives E=20 N/CE = 20 \text{ N/C} at r=3 mr = 3 \text{ m}. What is EE at r=6 mr = 6 \text{ m}?

Example 6

easy
Which way does the electric field point near a positive point charge?

Example 7

easy
Field lines from a negative point charge point ____ the charge.

Example 8

easy
A point charge Q=4 CQ = 4 \text{ C}. Find the field magnitude at r=2 mr = 2 \text{ m}. Use k=9×109k = 9\times10^9.

Example 9

easy
If the distance from a point charge doubles, the field becomes ____ as strong.

Example 10

medium
Two charges, +3 C+3 \text{ C} at x=0x=0 and +3 C+3 \text{ C} at x=4 mx=4 \text{ m}. What is the field magnitude at the midpoint x=2 mx=2 \text{ m}?

Example 11

easy
A charge Q=1 CQ = 1 \text{ C} at distance r=1 mr = 1 \text{ m}. Find EE. Use k=9×109k = 9\times10^9.

Example 12

easy
What are the units of electric field?

Example 13

hard
If QQ triples and rr halves, by what factor does the field of a point charge change?

Example 14

hard
Two point charges are placed on the x-axis: q1=+3×10−6 Cq_1 = +3 \times 10^{-6} \text{ C} at x=0x = 0 and q2=+3×10−6 Cq_2 = +3 \times 10^{-6} \text{ C} at x=0.4 mx = 0.4 \text{ m}. Find the electric field at the midpoint (x=0.2 mx = 0.2 \text{ m}). Use k=9×109k = 9 \times 10^9.

Example 15

medium
Field E1=300 N/CE_1 = 300\ \text{N/C} points east and E2=400 N/CE_2 = 400\ \text{N/C} points north at a point. Find the magnitude of the net field.

Example 16

medium
A uniform field of 500 N/C500 \text{ N/C} accelerates a +2 C+2 \text{ C} charge. Find the force.

Example 17

hard
A point charge +Q+Q produces E=100 N/CE = 100\ \text{N/C} at r=2 mr = 2\ \text{m}. What is EE at r=5 mr = 5\ \text{m}?

Example 18

medium
Charge +2 C+2 \text{ C} at origin. Find the field at r=3 mr = 3 \text{ m}. Use k=9×109k=9\times10^9.

Example 19

easy
A 4 C4\ \text{C} charge feels a force of 20 N20\ \text{N} at a point. What is the electric field at that point?

Example 20

challenge
Three charges +q+q sit at the vertices of an equilateral triangle of side aa. Find the magnitude of the field at the centroid.
← Back to Electric Field Worked Examples Formula Explained