If a source of $4 \ kW$ power emits $10^{20}$ photons/second,then this radiation belongs to which part of the electromagnetic spectrum?

$(i)$ The wavelength of microwaves is greater than that of $UV$-rays.
$(ii)$ The wavelength of $IR$ rays is less than that of $UV$-rays.
$(iii)$ The wavelength of microwaves is lesser than that of $IR$ rays.
$(iv)$ Gamma rays have the shortest wavelength in the electromagnetic spectrum.
Of the above statements:

The magnetic field in a plane electromagnetic wave is given by $B = 2 \times 10^{-7} \sin(0.5 \times 10^3 x + 1.5 \times 10^{11} t)$. This electromagnetic wave is .........

The range of wavelength for ultraviolet is from . . . . . . .

Consider the following statements regarding the electromagnetic spectrum:
$(A)$ The wavelength of microwaves is greater than that of $UV$ rays.
$(B)$ The wavelength of $IR$ rays is less than that of $UV$ rays.
$(C)$ The wavelength of microwaves is lesser than that of $IR$ rays.
$(D)$ Gamma rays have the shortest wavelength in the electromagnetic spectrum.
Which of the above statements are true?

Which of the following has the minimum frequency?