Which parameter is indicated by the number of waves passing through a given point in one second?

The ratio of the energy of a photon with wavelength $3000 \ \mathring{A}$ to that of a photon with wavelength $6000 \ \mathring{A}$ is:

What is the photoelectric effect? Explain it.

The radiation is emitted when a hydrogen atom goes from a high energy state to a lower energy state. The wavelength of one line in the visible region of the atomic spectrum of hydrogen is $6.5 \times 10^{-7} \, m$. The energy difference between the two states is:

The Vividh Bharati station of All India Radio,Delhi,broadcasts on a frequency of $1368 \, kHz$ (kilo hertz). Calculate the wavelength of the electromagnetic radiation emitted by the transmitter. Which part of the electromagnetic spectrum does it belong to?

What is electromagnetic radiation? How is it produced?