Practice Electric Charge in Physics

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

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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 5×1018 electrons flow past a point each second, what current does this represent?

Example 2

easy
How many coulombs of charge are carried by 1.25×1019 electrons?

Example 3

hard
A copper wire carries a steady 3.2 A. How many electrons pass a cross-section in 1 minute?

Example 4

challenge
A wire carries a steady current that delivers 1.6 C every 0.8 s. How many electrons pass per second?

Example 5

medium
A sphere carries −1.6 μC. How many excess electrons does it carry?

Example 6

challenge
Two identical spheres carry +8 C and +2 C. They touch and separate, then the +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 0 to 4 A over 10 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 C every 5 s. What current does this correspond to?

Example 14

medium
Sphere A has +6 C and touches identical sphere B with −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. A student claims the opposite plate must hold exactly +2.0 μC by conservation. Is this strictly required by conservation of charge alone? Explain.

Example 17

medium
A current of 250 mA flows for 8 s. How much charge passes, in coulombs?

Example 18

easy
If 2 C of charge passes a point in 4 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 5 extra electrons. What is the sign of its net charge?
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