Calculating Waves, wave lengths, frequency vibration, ...etc

Question

Hello i couldn't get these questions correct, please full setting out =] thanks

1) a singer sings into a microphone a note of frequency 500Hz. The microphone changes this to E.M.R of the same frequency. this is the audio wave. The radio transmitter combines this with the station carrier wave of frequency 104MHz, which means it beams into space at C(the speed of light). Find the wavelength of

a. the sound wave

b. the voice of E.M.R

c. the carrier wave

2) A water ripple contains 50 wave crests per meter and move outwards from the disturbance at 20cm sec-1. Find

a. the wave length

b. the frequency vibration

c.the time for the oscillation

Answer 1

The relation between frequency and wavelength is F*λ = c, where c = the wave velocity.

1)

a.  For the sound wave, c = 343 m/s. so for F = 500 Hz, λ = 343 / 500 m.

b.  If EMR = electromagnetic radiation, then c = 3*10^8 m/s and λ = 3*10^8/500 m

c.  ÃŽÂ» = 4*10^8 / 104*10^6

2)

a.  If there are 50 crests per meter, the the crests are 1/50 m apart and that is the wavelength.

b.  F = c/λ = 0.2/[1/50] = 0.2*50 = 10 Hz

c.  T = 1/F = 0.1 s