physics
posted by emily .
A certain radar installation used to track airplanes transmits electromagnetic radiation of wavelength 7 cm.
(a) What is the frequency of this radiation, measured in billions of hertz (GHz)? __________GHz
(b) What is the time required for a pulse of radar waves to reach an airplane 3 km away and return? ________s

a) use the wave equation
frequency*wavelength=speed of light
b) time= 2*3km/speedlght 
What is the time required for a pulse of radar waves to reach an airplane 7 km away and return?