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NEET2018PhysicsElectromagnetic WavesActual

Assume that a radio station is about 200 ~km away from your location and the station operates at 972 kHz . How long does it take for an electromagnetic signal to travel from the station to you and how many wave crests does it send out per second?

Options

  1. A666 s and 9.72 10^5 crests per second
  2. B666 s and 972 10^5 crests per second
  3. C555 s and 97.2 10^7 crests per second
  4. D555 s and 0.972 10^5 crests per second

Correct answer

A. 666 s and 9.72 10^5 crests per second

Step-by-step solution

Time taken by wave to travel = 200 ~km 3 10^5 ~km ~s ⁻¹ =6.667 10⁻⁴ ~s 666 s Number of crests per second = Frequency Frequency =972 kHz =9.72 10^5 ~Hz There are 9.72 10^5 crests per second.

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