The electric field of an electromagnetic wave travelling through a medium is given by $\overline{E}(x,t) = 25 \sin(2.0 \times 10^{15}t - 10^{7}x)\hat{n}$. The refractive index of the medium is . . . . . . . (All given measurements are in $SI$ units)

Identify the correct statements from the following descriptions of various properties of electromagnetic waves.
$A$. In a plane electromagnetic wave,the electric field and magnetic field must be perpendicular to each other,and the direction of propagation of the wave should be along the electric field or magnetic field.
$B$. The energy in an electromagnetic wave is divided equally between the electric and magnetic fields.
$C$. Both the electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of the wave.
$D$. The electric field,magnetic field,and direction of propagation of the wave must be mutually perpendicular to each other.
$E$. The ratio of the amplitude of the magnetic field $(B_0)$ to the amplitude of the electric field $(E_0)$ is equal to the reciprocal of the speed of light $(1/c)$.
Choose the most appropriate answer from the options given below:

$A$ light bulb emits power of $800 \, W$. What is the maximum value of the electric field at a distance of $3.5 \, m$ from the bulb in $V/m$?

The magnetic field in a plane electromagnetic wave is given by $\vec B = B_0 \sin(kx + \omega t) \hat j \ T$. The expression for the corresponding electric field will be (where $c$ is the speed of light).

In a plane electromagnetic wave,$U_E$ and $U_B$ are the average energy densities of the electric field and magnetic field,respectively. Then,which of the following is the correct option?

In a plane electromagnetic wave,the electric field oscillates sinusoidally at a frequency of $2 \times 10^{10} \, Hz$ and an amplitude of $48 \, V/m$. Find the amplitude of the magnetic field.