unit 9 - electromagnetism

magnetic field definition

A magnetic field is a region around a magnet, electric current, or moving charge where magnetic forces can be detected.

direction of magneitc field

By convention, field lines go from the North pole to the South pole outside the magnet.

Inside the magnet, they go from South to North, forming closed loops.

describe uniformity of the magnetic field around a bar magnet

Not uniform around a bar magnet:

Stronger at the poles, weaker at the middle.

Uniform magnetic field exists only between two parallel poles of a magnet where field lines are parallel and evenly spaced.

electromagnet definition

magnet created by electric current flowing through a coil of wires usually around a soft iron core

the magnetic field exists only when current flows

factors affecting the magnetic field

current (higher current, stronger field)

number of turns in the coil (more turns, stronger field)

key things abt magnetic fields

1. The magnetic field lines never intersect. 2. The closer they are, the stronger the magnetic field. 3. The region in between the like pole repulsion is known as the null region.

Induce temporary magnetism:

When a ferromagnetic material, such as iron or steel, is placed inside a solenoid’s active region and an electric current flows through the solenoid, the current produces a magnetic field. This magnetic field causes the tiny magnetic domains within the material to align in the same direction, magnetising the material. The magnetism remains only while the current is flowing, so the material becomes temporarily magnetised.