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# Tag Archives: permanent magnet

## Working of a microphone

How does a microphone do its work? Please explain me and can you give me answer in language Hindi I’m very thankful to you. (Shubham Agnihotri asked)

Microphone is a transducer (a device which converts energy from one form to another). The microphone converts sound energy to mechanical energy and then to electrical energy.

When we speak into the mic, the vibrations of the air produced by the sound make the diaphragm of the mic vibrate. A coil attached to the diaphragm vibrates together with it. The coil is moving in a strong magnetic field produced by a permanent magnet. Whenever the magnetic flux linked with coil changes an emf is induced in it. Therefor when we speak into the mic, an emf varying similar to the pressure variations produced by our sound is produced across the coil by electromagnetic induction.

If the ends of the coil is connected to an amplifier this can be amplified and can be send to the loudspeaker. The working of the loudspeaker is just the reverse of that of the microphone. I converts the electrical signal to sound signals.

## Electromagnetic induction in outer space and energy conservation

“lets pretend we are in space. and there  I have a permanent magnet rotor that and around it are copper windings. They do not touch and everything is floating with minimum friction (because we are in space)
imagine a generator with no brushes or bearings….

now my question is :
if i spin the rotor, and electrons start flowing on the copper(electricity)
would there be a negative force on the rotor to make it stop faster ?

Thank you

(Posted by )

Waiting for public response

## Devices using permanent magnets and electromagnets

1. List the devices where permanent magnets & electromagnets are used.
2. Sketch the pattern of the field lines around a current carrying:
• Straight Conductor

• Loop of wire

• Solenoid

Ans:

1. Permanent Magnets are used in
• Laboratory magnets
• loud speakers
• microphones
• cyclotron
• generators
• and many more
2. Pattern of the field lines around a current carrying

Straight Conductor

Loop of wire

Solenoid

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