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)? ANS: 4.2857GHz
b)What is the time required for a pulse of radar waves to reach an airplane 6 km away and return? ___s (note: it is not 2x10^-5)
2007-12-17 08:13:37 · 3 answers · asked by TheLostOne 3 in Science & Mathematics ➔ Physics
the relationship between wavelength, frequency and speed is: c = fL, so if you know L= 7 cm, and the speed of light is 3x10^5 km/s = 3x10^10 cm/s, then you can solve for f:
f=c/L = 3x10^10 cm/s / 7 cm = 0.429 x 10^10 Hz = 4.29 x 10^9 Hz
remember that you need the round trip distance of 12 km, so:
dist = speed x time =>
time = dist/speed = 12 km/3x10^5 km/s = 4x10^(-5)s
2007-12-17 08:30:16 · answer #1 · answered by kuiperbelt2003 7 · 0⤊ 0⤋
patr a. frequency = speed of light/wavelelngth = 3x10^8 m/s/0.07 m = 4.28 GHz --ok
part b. Round trip time, T = time to go out to plane and time to come back
T = R/c + R/c = 2R/c where R is distance to plane
T = 2*6x10^3 m/(3x10^8 m/s) = 40 microseconds = 4 x 10^-5 seconds
2007-12-17 08:26:21 · answer #2 · answered by nyphdinmd 7 · 1⤊ 0⤋
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2016-12-18 03:30:38 · answer #3 · answered by Anonymous · 0⤊ 0⤋