Question

Name the instrument which converts sound energy into electric energy.
A. Loudspeaker
B. Microphone
C. Dynamo
D. None

Answer 1

Hint: Energy can neither be created nor destroyed. It is only converted from one form to another form. There are many sources of energy. If we consider generators, it will convert mechanical energy into electrical energy. In the same way there will be a device which converts sound energy to electrical energy.

Complete answer:
In electromagnetic induction when a conductor is moving with certain velocity in the presence of magnetic field then voltage will be generated across the conductor and this is called the induced emf. This happens due to change in the flux which is associated with that conductor. Here mechanical energy is converted to electrical energy in this way.
Dynamo is such a device which converts mechanical energy to electrical energy.
In case of loudspeaker, the electrical signals are processed and they are converted into sound signals. So loudspeakers convert electrical energy to sound energy.
Now coming to the microphone, there will be a sensor which senses our voice and sends it to the transducer and there those signals are processed and converted to electrical signals. In this way, sound energy is converted to electrical energy.

Hence, option (B) is the correct answer.

Note:
In dynamo, usually they are kept in highly flowing water and water will rotate the blades of dynamo, which in turn rotates the coil and due to electromagnetic induction explained above the emf will be produced in the coil and current will be flown in it. So in this way electricity is generated. So we generally state that dynamo is a kind of generator which converts mechanical energy to electrical energy.