What are photons ? State their properties.

Explanation

### Step-by-Step Solution

**Step 1: Definition of Photons**
A photon is defined as a quantum or packet of energy that has zero rest mass. It is the fundamental particle of light and other forms of electromagnetic radiation. The energy of a photon is directly proportional to the frequency of the radiation and can be expressed mathematically by the equation:
\[ E = h \nu \]
where \( E \) is the energy of the photon, \( h \) is Planck's constant, and \( \nu \) (nu) is the frequency of the radiation.

**Step 2: Properties of Photons**
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