Summarizing Electric Field

Summary

• The electrostatic force field surrounding a charged object extends out into space in all directions.
• The electrostatic force exerted by a point charge on a test charge at a distance \(r\) depends on the charge of both charges, as well as the distance between the two.
• The electric field \(\mathbf{\text{E}}\) is defined to be

  \(\mathbf{\text{E}}=\cfrac{\mathbf{\text{F}}}{q,}\)

  where \(\mathbf{\text{F}}\) is the Coulomb or electrostatic force exerted on a small positive test charge \(q\). \(\mathbf{\text{E}}\) has units of N/C.

• The magnitude of the electric field \(\mathbf{\text{E}}\) created by a point charge \(Q\) is

  \(\mathbf{\text{E}}=k\cfrac{|Q|}{{r}^{2}}.\)

  where \(r\) is the distance from \(Q\). The electric field \(\mathbf{\text{E}}\) is a vector and fields due to multiple charges add like vectors.

Glossary

field

a map of the amount and direction of a force acting on other objects, extending out into space

point charge

A charged particle, designated \(Q\), generating an electric field

test charge

A particle (designated \(q\)) with either a positive or negative charge set down within an electric field generated by a point charge