1 Share your questions!

Share you questions around the sound theme which you are keen to explore!

For instance,

Why sound is important?
How sound is produced?

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How does a mic work?

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How does a speaker work.

I had done something interesting sometimes back.

I connected the speaker wires of the music system to the wires of a DC motor.

As I increased the volume I was surprised to find that the motor was producing sound. The sound was very low. Not like a speaker but you can hear it.

How is it possible?

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What is the principle on which a motor works?

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Found this on the internet.
"The working of DC motor is based on the principle that when a current carrying conductor is placed in a magnetic field, it experiences a mechanical force. "

The electricity sent to the dc motor converts it into magnetic force. It is repelled by the magnet in the motor body. So it moves forward. It can also move backward.
But the speakers only move forward and backward and not round in a circle. They produce sound by repulsion and attreaction of the coil in the speaker which moves the speker cone.

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A motor is a rotary actuator. Ie it rotates due to electromagnetic forces.
The speaker is linear actuator working on the same principle.

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How does a mic work?

Dont google just try to derive the working from the posts in this thread.

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Is it the same way a speaker works? I read somewhere that if we speak into a speaker it can become a mic. some device surrounded by a magnet in the mic produces electrical signals. But we have a scarlet studio in our home. It has a mic which requires 48v to work. Why do some mics require electricity?

IMG-20211007-WA0002

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Just as rotating motor by hand produces electricity, moving the speaker cone will produce a current. If the movment is caused by sound, the current produced will be an electrical replica of the sound wave.
However the signal thus produced is very small. One needs to amplify the signal. In good quality mikes this amplification is done by a circuit built into the mic. That is one reason for the mic needing 48 v.
However the need for this voltage is also dependent on the type of mic, of which there are many kinds.
The mic on our regular headset is known as an electret mic and uses the principle of capacitive charge transfer. It too has a very simple built in amplifier made of a single Field Effect Transistor and requires 3v to 5v to function.

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Inside the Scarlett cm25.
image

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