A plane electromagnetic wave of frequency 40 MHz travels in free space in the x-direction. At some point and at some instant, the electric field E has its maximum value of 750 N/C in y-direction. The wavelength of the wave is:
Correct answer: C. 7.5 m
- A. 3.5 m
- B. 5.5 m
- C. 7.5 m
- D. 9.5 m
Explanation
We use the formula v=fλ. For EMW v=c=3×10⁸m/s. Rearranging for λ and putting values we get,λ = c/f = 3×10⁸/40×10⁸ = 7.5m.Hence, this option is correct.
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Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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