Electromagnetism

An electromagnet is used in the earpiece of a telephone. The figure shows the simple structure of a telephone earpiece. When you speak to a friend through the telephone, your sound will be converted into electric current by the mouthpiece of the telephone. The current produced is a varying current and the frequency of the … Read more

A relay is an electrical switch that opens and closes under the control of another electrical circuit. The switch is operated by an electromagnet to open or close one or many sets of contacts. A relay has at least two circuits. One circuit can be used to control another circuit. The 1st circuit (input circuit) … Read more

When the switch is on, the circuit is completed and current flows. The electromagnet becomes magnetised and hence attracts the soft-iron armature and at the same time pull the hammer to strike the gong. This enables the hammer to strike the gong. As soon as the hammer moves towards the gong, the circuit is broken. … Read more

A solenoid is a long coil made up of a numbers of turns of wire. Magnetic Field Pattern Figure (a) illustrates the field pattern produced by a solenoid when current pass through it. The field lines in the solenoid are close to each other, indicates that the magnetic field is stronger inside the solenoid. We … Read more

Field Pattern Figure (a) below shows the field pattern produced by a current flowing in a circular coil. In SPM, you need to know the field pattern, the direction of the field and the factors affect the strength of the field. The direction of the field can be determined by the Right-Hand Grip Rule. Grip … Read more

Magnetic Field Pattern (Figure (a)) The magnetic field generated by a straight wire is concentric circles around the wire as shown in figure (a) above. Take notes that when the direction of the current is reversed, the direction of the magnetic field line is also reversed. The direction of the magnetic field line can be … Read more

When current passes through a conductor, the magnetic field will be generated around the conductor and the conductor becomes a magnet. This phenomenon is called electromagnetism.  Since the magnet is produced by electric current, hence it is called the electromagnet. An electromagnet is a type of magnet in which the magnetic field is produced by … Read more

In form 3, we learned that a magnet can attract certain type of metal. the metals that can be attracted by a magnet are called the “magnetic materials” of “ferromagnetic materials”. Examples of magnetic materials are iron, steel, nickel and cobalt. a magnet has 2 poles-the North Pole and the South Pole. there is a … Read more

Introduction to Magnetism (Revision) Electromagnet Electric Bell Electromagnetic Relay Circuit Breaker Telephone Earpiece Straight Wire (Video 1) Flat Coil Solenoid Apllications of Electromagnet Force on a Current Carrying Conductor Moving Coil Meter Direct Current Motor Loud Speaker Turning Effect of a Current-Carrying Coil in a Magnetic Field Force between 2 Current Carrying Conductor Electromagnetic Induction DC … Read more