JEE Previous Year Question

The electric field of a plane electromagnetic wave, travelling in an unknown nonmagnetic medium is given by, $E_y=20\text{sin}\text{⁡}(3\times {10}^{6}x-4.5\times {10}^{14}t)V/m$ (where $x\text{,}t$ and other values have S.I. units). The dielectric constant of the medium is $\text{\_}\text{\_}\text{\_}\text{\_}$ (speed of light in free space is $3\times {10}^{8}m/s$ )

Topic: JEE PYQ

Answer: 4. Full step-by-step solution below.