## What is the difference between fields and charges (magnetic and electric)?

#### What is the difference between fields and charges (magnetic and electric)?

Electric charges themselves push and pull on one another via electrostatic forces. Magnetic poles push and pull on one another via magnetostatic forces. We can also think of the forces that various electric charges exert on one charge that you’re hold as being caused by some property of the space at which that one charge is located. We call that property of space an electric field and say that the charge is being pushed on by the electric field. We could do the same with magnetic poles and a magnetic field. But these two fields are more than just a useful fiction. The fields themselves really do exist. You can see that whenever moving electric charge creates a magnetic field or when a moving magnetic pole creates an electric field. Light consists only of electric and magnetic fields.

## What materials are magnets made of?

#### What materials are magnets made of?

They are mostly iron, cobalt, or nickel, which are intrinsically magnetic metals. But to help them retain their magnetic alignments, permanent magnets have other elements in them, too. Iron is magnetic at the microscopic scale, but that magnetism is broken up into lots of tiny regions that all point in random directions. To make a whole piece of iron magnetic, something must help those tiny regions stay pointing in the same direction. The good permanent magnets have structures that keep all the tiny regions pointing in one direction.

## How can currents and electromagnets encounter frictional effects without touchin…

#### How can currents and electromagnets encounter frictional effects without touching?

When you slide a strong magnet quickly above a metal surface, there is a friction-like magnetic drag effect. This effect occurs even when the two objects don’t touch. The origin of this effect lies in the repulsions between the metal and magnet: it’s strongest slightly in front of the moving magnet so the magnet encounters some difficulty heading forward. The reason why the magnetization of the metal is strongest slightly in front of the moving magnet is related to the loss of energy by current moving in the metal. The magnetization (of the metal surface) in front of the moving magnet is fresher than the magnetization behind it. The current responsible for the magnetization behind the magnet has been flowing for long enough to have lost energy. But the faster you move the magnet across the metal surface, the less time the currents in it have to lose energy and the less friction-like force the magnet experiences.

## How does a magnet induce a metal to become attracted to the magnet? Does the met…

#### How does a magnet induce a metal to become attracted to the magnet? Does the metal become a magnet also?

A steady, motionless magnet can’t induce a piece of normal metal (not iron, cobalt, or nickel) to become magnetic. Only a moving or changing magnet can do that. When a metal is exposed to a changing or moving magnet, it does become magnetic. That metal becomes a type of magnet; an electromagnet. The metal itself isn’t really the magnet; the electric charges inside it are. These charges move in response to the changing or moving magnet nearby and they become magnetic, too. The effect is always repulsive, not attractive. The temporarily magnetic metal repels the magnet that is making it magnetic.