The band gap between the valence and the conduction bands in zinc oxide `(ZnO)`is 3.0eV.Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation .Find the maximum wavelength that can be emitted in this process.

Explanation

To find the maximum wavelength that can be emitted when an electron in the conduction band of zinc oxide (ZnO) combines with a hole in the valence band, we can follow these steps:

### Step 1: Understand the Energy Band Gap
The band gap energy (Eg) between the valence band and the conduction band in ZnO is given as 3.0 eV. When an electron transitions from the conduction band to the valence band, it releases energy equal to this band gap.

### Step 2: Relate Energy to Wavelength
The energy (E) of the emitted electromagnetic radiation can be related to its wavelength (λ) using the equation:
\[ E = \frac{hc}{\lambda} \]
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