Practice Electric Charge in Physics

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

Quick Recap

A fundamental property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).

Some particles carry an invisible 'label' — positive or negative — that makes them push or pull on each other.

Showing a random 20 of 50 problems.

Example 1

medium
If 5×10185\times10^{18} electrons flow past a point each second, what current does this represent?

Example 2

easy
How many coulombs of charge are carried by 1.25×10191.25\times10^{19} electrons?

Example 3

hard
A copper wire carries a steady 3.2 A3.2\ \text{A}. How many electrons pass a cross-section in 1 minute1\ \text{minute}?

Example 4

challenge
A wire carries a steady current that delivers 1.61.6 C every 0.80.8 s. How many electrons pass per second?

Example 5

medium
A sphere carries 1.6 μC-1.6\ \mu\text{C}. How many excess electrons does it carry?

Example 6

challenge
Two identical spheres carry +8+8 C and +2+2 C. They touch and separate, then the +5+5 C sphere (now equalized) touches a third identical sphere that was neutral. What charge ends on the third sphere?

Example 7

easy
How many electrons make up approximately one coulomb of charge?

Example 8

hard
A wire delivers a current that rises linearly from 00 to 4 A4\ \text{A} over 10 s10\ \text{s}. How much charge passes in that interval?

Example 9

easy
Charging a balloon by rubbing it transfers electrons. Is new charge created?

Example 10

easy
A proton and an electron are released from rest near each other. What kind of force do they feel?

Example 11

easy
Fill in the blank: charge is measured in ____.

Example 12

easy
Two objects both carry positive charge. Do they attract or repel?

Example 13

medium
A point passes 0.6 C0.6\ \text{C} every 5 s5\ \text{s}. What current does this correspond to?

Example 14

medium
Sphere A has +6+6 C and touches identical sphere B with 2-2 C. After contact, what charge does each carry?

Example 15

easy
A neutral atom loses one electron. What is its net charge?

Example 16

challenge
A capacitor plate holds 2.0 μC-2.0\ \mu\text{C}. A student claims the opposite plate must hold exactly +2.0 μC+2.0\ \mu\text{C} by conservation. Is this strictly required by conservation of charge alone? Explain.

Example 17

medium
A current of 250250 mA flows for 88 s. How much charge passes, in coulombs?

Example 18

easy
If 22 C of charge passes a point in 44 s, is this asking about charge, current, or voltage?

Example 19

easy
A positive charge and a negative charge are brought near each other. Do they attract or repel?

Example 20

easy
An object gains 55 extra electrons. What is the sign of its net charge?