Write the expression for velocity of electromagnetic waves.

Explanation

To derive the expression for the velocity of electromagnetic (EM) waves, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding EM Waves**:
- Electromagnetic waves consist of oscillating electric fields (E) and magnetic fields (B). The energy density associated with the electric field is given by \( \frac{1}{2} \epsilon_0 E^2 \) and for the magnetic field, it is \( \frac{1}{2} \frac{B^2}{\mu_0} \).

2. **Energy Density Equivalence**:
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