Question

Physics?

During football games we sometimes see TV crews on the sidelines holding dishes with microphones. What would be the advantage of a dish? What determines the size of the dish?

Answer 1

Tis the season for inverse square law

Answer 2

For the first question I answered that the dish allows you to amplify the audio signal by concentrating the sound at the focal point (where the microphone is). However, i'm not sure about the second question.

Answer 3

Looks like you gotta do some research e-e

Answer 4

http://www.satsig.net/focal-length-parabolic-dish.htm

I found this link, but I am still unsure...

Answer 5

Why didn't they just say microphone, but any case you have the right idea, it's to focus onto the receiver, and some sounds waves are much lower so they require larger dishes

Answer 6

What do you mean by the soundwaves being "lower"?

Answer 7

Here just read this https://en.wikipedia.org/wiki/Parabolic_microphone

Answer 8

"This is because, from the Rayleigh criterion, parabolic dishes can only focus waves with a wavelength much smaller than the diameter of their aperture."

Answer 9

Rayleighs Criterion is sin(theta)=1.22*lamda/d

Answer 10

so the wavelength has to be much smaller because sin(theta) can not be greater than 1?

Answer 11

Not specifically 1, depends on the diameter of the aperture

Answer 12

ah thats what I meant...it made sense in my head lol...

I was thinking about how sin(theta) ranges from -1 to 1, so the wavelength has to be much smaller than the diameter of the aperture so that 1.22*wavelength/diameter is less than or equal to 1.

Answer 13

But I think this makes sense to me now... thank you so much! :3

Answer 14

I think you have the idea, and yw :)