# Plz help me out..ASAP..A 75-kHz radio transmitter sends an electromagnetic wave to a receiver L = 20.0 km away?

A 75-kHz radio transmitter sends an electromagnetic wave to a receiver L = 20.0 km away.The signal also travels to the receiver by another path where it reflects from a helicopter as shown. Assume that there is a 180° phase shift when the wave is reflected.

(a) What is the wavelength of this EM wave?

answer in km

please answer this question...10pts best answer..it would be greatly appreciated...thank you very much :)

### 1 Answer

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- ?Lv 410 years agoFavourite answer
Lots of extra information that is not really needed.

All you need to know is: c = νλ = frequency * wavelength where c = 3.8E8 m/sec aka speed of light.

solve for the wavelength λ = c/ν

λ = (3E8m/sec)/(75000/sec) 1Hz = 1/sec

λ = 4000m or 4km

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