electrodynamics

what is alternating current

direction of current changes every half rotation

what is a magnetic field

A magnetic field is a region in space around a magnet where other magnets or ferromagnetic

materials will experience a force without having any physical contact.

• All magnets have a polarity, i.e. they have two opposite poles, a north pole (N) and south pole be

How can you increase the magnetic field around the solenoid?

• The magnetic field around a solenoid can be strengthened by:

> Increasing the current in the coils

Increasing the number of turns in the solenoid

• Inserting a soft iron core into the centre of the solenoid (called an electromagnet)

What is direct current

• Current which flows in a constant direction, and possesses a voltage with constant polarity

produced by batteries (with fixed positive and negative

terminals) or by DC generators.

What is a diode ?

The diode is an electronic device that allows current to flow in one direction only. 0.4V

Structure:

• Diodes are made from semi-conductor materials, most commonly silicon (Si) or Germanium

State lenz law

The induced current on a conductor flows in such a way to oppose the change in magnetic flux