The ratio of the magnitude of the magnetic field $(B_0)$ and electric field intensity $(E_0)$ of a plane electromagnetic wave in free space with permeability $\mu_0$ and permittivity $\varepsilon_0$ is (Given that $c$ is the velocity of light in free space):

$A$ cube of unit volume contains $35 \times 10^7$ photons of frequency $10^{15} \text{ Hz}$. If the energy of all the photons is viewed as the average energy being contained in the electromagnetic waves within the same volume,then the amplitude of the magnetic field is $\alpha \times 10^{-9} \text{ T}$. Taking permeability of free space $\mu_0 = 4\pi \times 10^{-7} \text{ Tm/A}$,Planck's constant $h = 6 \times 10^{-34} \text{ Js}$ and $\pi = \frac{22}{7}$,the value of $\alpha$ is $.....$

The ratio of the amplitude of the magnetic field to the amplitude of the electric field for an electromagnetic wave propagating in vacuum is equal to:

To radiate $EM$ signal of wavelength $\lambda$ with high efficiency,the antennas should have a minimum size equal to

The condition under which a microwave oven heats up a food item containing water molecules most efficiently is

The electric field in an electromagnetic wave is given by $\overrightarrow{E} = \hat{i} 40 \cos \omega(t - \frac{z}{c}) \text{ N/C}$. The magnetic field induction of this wave is (in $SI$ units):