The energy that will be ideally radiated by a $100\,kW$ transmitter in $1$ hour is:

$A$ microwave and an ultrasonic sound wave have the same wavelength. Their frequencies are in the ratio (approximately):

According to the theoretical study of radiation from a linear antenna,the power radiated is proportional to $[\lambda = \text{wavelength}]$

The power radiated from a linear antenna of length $l$ is proportional to (Given,$\lambda =$ wavelength of the wave):

For an $EM$ wave,the electric and magnetic fields are $300 \ V m^{-1}$ and $7.9 \ A m^{-1}$ respectively. The maximum rate of energy flow is, (in $W m^{-2}$)

The electric field intensity produced by the radiation coming from a $100 \, W$ bulb at a distance of $3 \, m$ is $E$. The electric field intensity produced by the radiation coming from a $60 \, W$ bulb at the same distance is $\sqrt{\frac{x}{5}} E$. The value of $x$ is ......... .