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.
Example 1
easyAn object has an excess of 3.0 \times 10^{13} electrons. What is the total electric charge on the object? Use e = 1.6 \times 10^{-19} \text{ C}.
Example 2
mediumTwo charged spheres carry charges of +5 \text{ } \mu\text{C} and -3 \text{ } \mu\text{C}. They are brought into contact and then separated. What is the charge on each sphere afterward?
Example 3
mediumA current of 2 \text{ A} flows through a wire for 30 \text{ s}. How many electrons pass through the wire? Use e = 1.6 \times 10^{-19} \text{ C}.
Example 4
hardA Van de Graaff generator accumulates charge on a metal sphere of radius 0.15 \text{ m}. If the electric field at the surface reaches 3 \times 10^6 \text{ V/m} (air breakdown), what is the maximum charge on the sphere? Use k = 9 \times 10^9 \text{ N m}^2/\text{C}^2.