What is the velocity of electromagnetic waves in conductors?

In a plane $EM$ wave,the electric field oscillates sinusoidally at a frequency of $30 \text{ MHz}$ and amplitude $150 \text{ V/m}$. Identify the correct expression for $\vec{B}$ assuming the wave is propagating along the $x$-axis and the electric field is oscillating along the $y$-axis.

All components of the electromagnetic spectrum in vacuum have the same

Three observers $A, B$ and $C$ measure the speed of light coming from a source. Observer $A$ moves towards the source,observer $C$ moves away from the source with the same speed,and observer $B$ remains stationary. The surrounding space is a vacuum everywhere. Which of the following is true regarding the measured speeds ${v_A}, {v_B}$ and ${v_C}$?

What physical quantity is the same for $X$-rays of wavelength $10^{-10} \; m$,red light of wavelength $6800 \; \mathring{A}$,and radio waves of wavelength $500 \; m$?

In a two-wire transmission line,the power flows .......