Wrap-Up Electric and Magnetic Forces

Magnetism *Field lines: never cross, show the invisible magnetic field *Strongest on the ends *Like poles repel *Opposite poles attract *The earth is a magnet

The strength of electric force depends on… Amount of Charge The more charged particles there are in an object, the stronger it will attract or repel another object.

The strength of electric force depends on… Distance between objects The closer two objects are, the stronger the attraction or repulsion.

Why do you hear a zap as you touch something with static charge?

How does lightning work? Is it static electricity, too?

How does force relate to distance on a graph?

Have you ever heard of a magnet deactivating a credit card? The ­stripe on the back of a credit card is a magnetic stripe, often called a magstripe. The magstripe is made up of tiny iron-based magnetic particles in a plastic-like film. Each particle is really a very tiny bar magnet about 20 millionths of an inch long. The magstripe can be "written" because the tiny bar magnets can be magnetized in either a north or south pole direction. This represents the numbers on the front of the card.

Quiz on Thursday Static Electricity Magnets Electromagnets