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JAMB Physics 1993 Question 23

Question 23

Electromagnetic Spectrum

Radio waves emitted from an antenna are picked up by a radar after reflection from an aircraft in 4 × 10−3 s. How far is the aircraft from the antenna? [c = 3 × 108 m s−1]

  1. A.6.0 × 102 km
  2. B.1.2 × 103 km
  3. C.3.0 × 103 km
  4. D.6.0 × 105 km.
Show the answer and explanation

Answer: A (6.0 × 102 km)

Explanation

The waves go there and back, so distance = c × t/2 = 3 × 108 × 2 × 10−3 = 6.0 × 105 m = 6.0 × 102 km.