Which of the following waves has the maximum wavelength?

The power of a source is $4 \, kW$. If it produces $10^{20}$ photons in $1 \, s$,then the radiation emitted from this source belongs to which part of the electromagnetic spectrum?

Write the range of frequencies of visible light.

$X$-rays and gamma rays are both electromagnetic waves. Which of the following statements is true?

The correct order of electromagnetic waves with increasing frequency is

The wavelengths of Gamma rays,$X$-rays,and microwaves are respectively $\lambda_r, \lambda_x$,and $\lambda_m$. Then which of the following relations is correct?