Wavenumber for a radiation having $5800 \ \mathring{A}$ wavelength is $x \times 10 \ cm^{-1}$. The value of $x$ is . . . . . . . .

What is Maxwell's electromagnetic theory?

What is an emission spectrum?

Which characteristics of electromagnetic radiation can be explained by its wave nature and particle nature,respectively?

When electromagnetic radiation of wavelength $300 \, nm$ falls on the surface of a metal,electrons are emitted with the kinetic energy of $1.68 \times 10^5 \, J \, mol^{-1}$. What is the minimum energy needed to remove an electron from the metal? $(h = 6.626 \times 10^{-34} \, J \, s, c = 3 \times 10^8 \, m \, s^{-1}, N_A = 6.022 \times 10^{23} \, mol^{-1})$

The laser in an audio compact disc uses light of wavelength $7.8 \times 10^2 \ nm$. What is the frequency of light emitted by the laser?