GATE 2015 EC – Question 35
The electric field component of a plane wave traveling in a lossless dielectric medium is given by $\vec{E}(z, t) = \hat{a}_y 2\cos\left(10^8 t - \frac{z}{\sqrt{2}}\right)$ V/m. The wavelength (in m) for the wave is ________.
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Correct answer: 8.85 to 8.92
Explanation
Comparing with $\cos(\omega t - \beta z)$, the phase constant is $\beta = \frac{1}{\sqrt{2}}$ rad/m. The wavelength is $\lambda = \frac{2\pi}{\beta} = 2\pi\sqrt{2} = 8.886$ m.