28-06-2012, 01:29 PM
Electricity and Magnetism – Lecture 3Electric Field
Electricity and Magnetism.ppt (Size: 2.23 MB / Downloads: 240)
Vector Field Due to Gravity
When you consider the force of Earth’s gravity in space, it points everywhere in the direction of the center of the Earth. But remember that the strength is:
This is an example of an inverse-square force (proportional to the inverse square of the distance).
Idea of Test Mass
It is convenient to ask what is the force per unit mass. The idea is to imagine putting a unit test mass near the Earth, and observe the effect on it:
Electric Field
Electric field is said to exist in the region of space around a charged object: the source charge.
Concept of test charge:
Small and positive
Does not affect charge distribution
Electric field: