Electromagnetism Electromagnetism Describes the magnetic field produced by
Electromagnetism
Electromagnetism • • • Describes the magnetic field produced by a current-carrying wire (righthand rule or left-hand rule) Names ways of modifying the intensity of the magnetic field produced by a current-carrying wire (type of wire, current intensity) Compares the behaviour of a compass in the magnetic field of a magnet with the magnetic field created by a current-carrying wire Describes the magnetic field produced by a solenoid (right-hand rule or left-hand rule) Names ways of changing the intensity of the magnetic field produced by a solenoid (nature of the core, intensity of the current, number of turns) Names ways of inducing electrical current in a wire (e. g. movement of a magnet, changing the intensity of a magnetic field)
Electromagnetism • How do magnets react? • Right hand rule – (straight wire and solenoid) • Increase magnetic field – (straight wire and solenoid) • How to generate electricity?
Recap on Magnetism • Magnetism: – All phenomena caused by magnets • A magnet is an object that can attract other objects containing iron, cobalt or nickel
Magnetism • Have you ever noticed? – It doesn’t matter which part of the magnet you bring to iron, it will always attract to a magnet. – Why? • Iron is made up of small polarized regions called domains. Each of these act like a small magnet. When you magnetize the iron, the domains align to be attracted to the magnet. Remember opposites attract
• *** IRON, COBALT, NICKEL
Magnetism • Attraction and Repulsion – Opposites attract – Like poles repel
Electromagnetism • Electromagnetism: – All phenomena resulting from the interaction between electricity and magnetism. – Right Hand rules: • Live Wire – Thumb points to the negative terminal – Fingers show the direction of the magnetic field
Electromagnetism • Right Hand rule – Solenoids (a cylindrical coil of live wire) • You fingers follow the coil and point towards the negative terminal • Your thumb indicates the magnetic North
Electromagnetism • How can you tell what is the negative terminal? – In the circuit drawings the negative terminal will either be identified with a – Or… – In the following symbol the shorter terminal is the negative one
Electromagnetism • You can generate an electrical field by… – Moving a conductor in a magnetic field – Moving a magnet around a conductor
• Magnetic field of a life wire – The thumb points in the direction of conventional current – The fingers show the direction of the magnetic lines
• Will the magnetic field be clockwise or counter clock wise
• What are the two poles?
- Slides: 14