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QJEEM17Phcbe7: JEE Main 2017 Physics - Class 12 JEEM17Phcbe7 Solution: A signal is to be transmitted through a wave of wavelength λ ,…

A signal is to be transmitted through a wave of wavelength λ, using a linear antenna. The length l of the antenna and effective power radiated Peff will be given respectively as :

(K is a constant of proportionality)

Multiple Choice Options

  • A λ, Peff = K (1λ)2
  • B λ8, Peff = K (1λ)
  • C λ16, Peff = K (1λ)3
  • D λ5, Peff = K (1λ)(1λ)12

Step-by-Step Verified Solution

We know that for a linear antenna of length l, (i) it's length of antenna is comparable to the wavelength of the signal and (ii) the power radiated is proportional to 1/λ2. That is, the power radiated for the antenna increases with decreasing λ thereby increasing the frequency.

Power of the antenna P=μ(1l)2

Here, μ = K; hence, the correct option is (D).

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