The electric field associated with an electromagnetic wave propagating in a dielectric medium is given by E = 30 ( 2 x ^ + y ^ ) sin [ 2 π ( 5 × 1 0 14 t − 3 1 0 7 z ) ] V m − 1 . Which of the fol

Question

The electric field associated with an electromagnetic wave propagating in a dielectric medium is given by E = 30 ( 2 x ^ + y ^ ​ ) sin [ 2 π ( 5 × 1 0 14 t − 3 1 0 7 ​ z ) ] V m − 1 . Which of the following option(s) is(are) correct? [Given: The speed of light in vacuum, c = 3 × 1 0 8 ms − 1 ]

TestHub · Accepted Answer

The phase speed and refractive index are $v = \frac{5 \times 1 0 ^{14}}{1 0 ^{7} /3} = 1.5 \times 1 0^{8} m/s, n = \frac{3 \times 1 0 ^{8}}{v} = 2$

Propagation is along +z, so B=(1/v) k-hat cross E. Its vector is $B = 2 \times 1 0^{- 7} (- \hat{i} + 2 \hat{j}) sin [2 π (5 \times 1 0^{14} t - \frac{1 0 ^{7} z}{3})] T$

The x-component amplitude is -2 x 10^-7 T (A correct); the y-component amplitude is 4 x 10^-7 T (B wrong). Propagation is +z, so C is wrong. The refractive index is 2 (D correct). Answer: A,D.

Physics - EM Waves Question with Solution | TestHub

Options:(select one or more)

Doubts & Discussion

JEE Advanced 2027 (Class 12)