You’ll be surprised at the number of magnets that are under your roof…
Vacuum cleaner magnet
Electromagnetism is used here to produce the desired effect. A magnetically conducting material is inside the motor of the vacuum cleaner. When an electric current is introduced to a coil around the material, repulsive forces make the motor spin. The material loses its magnetism when the vacuum is turned off.
Magnet in microwave
Inside a microwave oven is a magnetron, which contains magnets. Strong permanent magnets are mounted inside this tube. When electricity passes through the magnetron, the resultant electric and magnetic fields produce electromagnetic energy in the form of microwaves.
For a buzzer-style doorbell, pressing the button moves and releases a contact from an electromagnet to break and complete a circuit. A chiming doorbell, meanwhile, moves an iron core through an electromagnet coil and back when the button is pressed, hitting two chime bars in sequence.
Like credit cards, the storage disks inside computers are coated with bits of iron. By changing the magnetic orientation of the iron, a pattern can be created to store a particular set of data. This pattern can be read by the computer and replicate the data on screen. The monitor itself uses magnets in the same way as an old cathode ray tube TV.
Most modern LCD or plasma TVs don’t use magnets. However, older models use a cathode ray tube to fire electrons against the back of the screen. Coated in phosphor, parts of the screen glow when struck by the beam. Coils produce magnetic fields that move the beams horizontally and vertically to produce the desired picture.
All credit cards have a black strip on them, known as a magnetic stripe. Inside, minuscule bits of iron are held in a plastic film. These can be magnetized in a north or south direction to store important data. When you swipe the card through a machine, the line of tiny magnets is read and information is obtained.
Magnet in speakers
Using electromagnetism, most speakers contain a stationary magnet and a wire coil inside a semi-rigid membrane. When a current runs through the coil, the membrane rotates in and out because of the force between coil and magnet, creating vibrations that produce sound. Phone speakers use this same mechanism, only smaller.