The electromagnetic flux from the sun reaching the earth is $10^3 \, W/m^2$. The power incident on a roof of dimensions $8 \, m \times 20 \, m$ is ..... $W$.

The magnetic field in a plane electromagnetic wave is given by
$B_y = (2 \times 10^{-7}) \sin (0.5 \times 10^3 x + 1.5 \times 10^{11} t) \, T$
$(a)$ What is the wavelength and frequency of the wave?
$(b)$ Write an expression for the electric field.

An $EM$ wave from air enters a medium. The electric fields are $\overrightarrow {{E_1}} = {E_{01}}\hat x\cos[2\pi v(\frac{z}{c} - t)]$ in air and $\overrightarrow {{E_2}} = {E_{02}}\hat x\cos[k(2z - ct)]$ in medium,where the wave number $k$ and frequency $v$ refer to their values in air. The medium is nonmagnetic. If $\varepsilon_{r_1}$ and $\varepsilon_{r_2}$ refer to relative permittivities of air and medium respectively,which of the following options is correct?

If the rms value of the electric field of electromagnetic waves at a distance of $3 \ m$ from a point source is $3 \ N C^{-1}$,then the power of the source is (in $W$)

$A$ point light source emits electromagnetic ($E$.$M$.) waves in free space. $A$ detector, placed at a distance of $L \text{ m}$, measures the intensity as $I_o$. The detector is now shifted to another location on the same spherical surface, ensuring the angle between the original location and the new location is $45^{\circ}$. The measured intensity at the new location will be . . . . . . .

The electric field and magnetic field components of an electromagnetic wave going through vacuum are described by
$E_x = E_0 \sin(kz - \omega t)$
$B_y = B_0 \sin(kz - \omega t)$
Then the correct relation between $E_0$ and $B_0$ is given by