What is the displacement variable in a simple pendulum and the propagation of light?

$A$ plane electromagnetic wave of wavelength $3.0 \ m$ travels in vacuum along the positive $X$-axis. The electric field of amplitude $300 \ Vm^{-1}$ oscillates parallel to the $Y$-axis. Then the intensity of the wave is $(\mu_0 = 4\pi \times 10^{-7} \ Hm^{-1}, c = 3 \times 10^8 \ ms^{-1})$ (in $Wm^{-2}$)

The velocity of electromagnetic radiation in a medium of permittivity $\varepsilon_0$ and permeability $\mu_0$ is given by:

$A$ microwave oven heats food containing water molecules very efficiently under which of the following conditions?

$A$ plane electromagnetic wave is propagating along the direction $\frac{\hat{i}+\hat{j}}{\sqrt{2}},$ with its polarization along the direction $\hat{k}$. The correct form of the magnetic field of the wave would be (here $B_{0}$ is an appropriate constant)

Assertion $(A):$ $A$ charge moving in a circular orbit can produce electromagnetic waves.
Reason $(R):$ The source of electromagnetic waves should be in accelerated motion.