Science Magazine: March 2015

Wednesday, 25 March 2015

Friday, 13 March 2015

ELECTROMAGNETS - MAGNETS THAT CAN BE TURNED ON OR OFF

WHAT IS AN ELECTROMAGNET?

An electromagnet is a magnet that is created using an electric current. When an electric current flows in a wire it creates a magnetic field. By winding the wire into a coil we can strengthen the magnetic field. We can make an even stronger electromagnet by winding wire around a metal core, for example, an iron nail.When electricity passes through the wire, a magnetic field is created around the nail. The advantage of electromagnets is that, unlike ordinary magnets, they can be turned on or off, by connecting or disconnecting the electric source. This makes the applications of electromagnets endless. The magnetic force created by electromagnets can strengthened or weakend by increasing or decreasing the electric current or by adding more turns to the coil.

Electromagnets are used in many electronic devices including hard disk drives, speakers, motors and generators.

This experiment was presented two years ago in the school science fair. It is a fun way to explain and understand how electromagnets work. To make this device a shoe box, card, string, a match box were used. For the electromagnet, a nail, wire, and a battery and a piece of card and paper clip to make a switch. How to play? Switch on the electromagnet and stick a small metal to it. Push the match box, until it begins to swing. Now try to make the metal fall in the box by switching the electromagnet off.