What is photon ? Write formula for its energy.

Explanation

**Step-by-Step Solution:**

1. **Definition of a Photon:**
A photon is a fundamental particle of light and is considered a quantum of electromagnetic radiation. It is an energy packet that is emitted during various processes, such as when an electron transitions between energy levels in an atom or when a charged particle accelerates.

2. **Energy of a Photon:**
The energy (E) of a photon can be expressed using two different formulas:
- The first formula relates energy to frequency:
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