JEE Mains · Physics · STD 12 - 8. Electromagnetic waves
Due to presence of an em-wave whose electric component is given by \(\mathrm{E}=100 \sin (\omega \mathrm{t}-\mathrm{kx}) \mathrm{NC}^{-1}\), a cylinder of length 200 cm holds certain amount of em-energy inside it. If another cylinder of same length but half diameter than previous one holds same amount of em-energy, the magnitude of the electric field of the corresponding em-wave should be modified as
- A \(400 \sin (\omega \mathrm{t}-\mathrm{kx}) \mathrm{NC}^{-1}\)
- B \(200 \sin (\omega t-k x) \mathrm{NC}^{-1}\)
- C \(50 \sin (\omega \mathrm{t}-\mathrm{kx}) \mathrm{NC}^{-1}\)
- D \(25 \sin (\omega \mathrm{t}-\mathrm{kx}) \mathrm{NC}^{-1}\)
Answer & Solution
Correct Answer
(B) \(200 \sin (\omega t-k x) \mathrm{NC}^{-1}\)
Step-by-step Solution
Detailed explanation
Energy density of an \(E M_{\text {wave }}=\frac{1}{2} \varepsilon E_0^2\), whare \(E_0\) is the amplitude of the wave. Since total energy is same for both cylinders…
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