What is forbideen energy gap?

Suppose that the energy liberated in the combination of a hole-electron pair is conveted into electromagnetic radiation.If the maximum waveelngth of the radiation emitted is 630 nm,what is the width of forbbidden energy gap?

Find the maximum wavelength of electromagnetic radiation,which can create a hole-electron pair in germanium.Given that forbidden energy gap in germanium is 0.72 eV.

The energy liberated in the ecombination of hole-electron pair is converted into electromagnetic radiation. If the aximum wave length emitted is 600 nm, find the value of forbidden energy gap.

The energy liberated in the ecombination of hole-electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 500 nm, find value of forbidden energy gap.