Posts Tagged ‘sound’

Can light do some mechanical work?

“We know that sound can cause some mechanical work(eg:when we keep our hand in front of a large speaker,we feel something hitting the back of our hand), but why this doesn’t happen with light??” -Manishankar asks.

Relativity, Black Hole and some doubts

In the model of the big bang I would like to pose the following question. My understanding is that

1. The expansion of the universe is accelerating and

2. The radiation or shock wave to keep the analogy going is something we can measure.

My question is this. While we can rewind the clock to a single moment when the universe was infinity dense how do we know that this was a moment at all. Let me elaborate. As the universe expands could time or space time not also expand and if so than when the big bang occurred is something we cannot measure merely by rewinding the clock. If we are experiencing time at a given rate when the universe is at its current size would time not be being effected by the expansion also and if so would that mean the there was simply no start and no end to the universe? Perhaps the big bang is not as accurate as we may wish and perhaps it is our ability to comprehend that is limited. I propose there is no start or end to the universe it has always and will always be as it, and we, cannot exist without time and as such these two objects or things form a symbiotic relationship with each other. While the universe expands so does time and its effects are reduced in line with its expansion. Does this sound plausible and if not why?

Question from Beats (Waves)

Sanjeet asked:

"the displacement of a particle in periodic motion is given by "y=(cos2t-2cost+2sin^2t+1). What is the no. of beats that can be heard in 10 seconds?"

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)

Answer:

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.

(Please use Google Translate  or Click Here to get the Hindi Version)