white noise generator
Everything past this point is notes
Electromagnets are also used in loudspeakers. You have a voltage that is dependent on the sound's pitch and volume which turns a magnetic field on and off, setting the loudspeaker vibrating.
Microphone = Records sound
The Loud Speaker
|A cut through diagram of a typical speaker|
A speaker consists of a paper cone attached to a coil which acts as a small electromagnet. The coil is fitted over a permanent magnet, and as the current flows through the coil it is either attracted or repelled depending on which direction the current flows. A typical signal from an amplifier will be a varying a.c. current, and so the cone will vibrate back and forth at the same frequency as the current. As the cone vibrates, it sets up pressure waves in the air, which we hear as sound.
The electric bell
Once the battery is connected a current flows in the wire loops around the U shaped soft iron core.
This turns the core into an electromagnet.
The electromagnet attracts the amateur which is also made of soft iron.
As the amateur moves towards the electromagnet, it causes the hammer to strike the bell. At the same time it breaks the circuit at X.
The break in the circuit causes the current to stop flowing.
The soft iron cores loses it's magnetic field and releases the amateur which springs back to its original position.
The contact screw touches the springy metal and completes the circuit. The whole cycle is repeated over and over until the battery is disconnected or runs down.