Electromanetic waves travel in a medium with a speed of `2 xx 10^(8) ms^(-1)`. The relative magnetic permeability of the medium is 1. Find the relative electrical permittivity.

Explanation

To find the relative electrical permittivity (\( \epsilon_r \)) of a medium in which electromagnetic waves travel at a speed of \( 2 \times 10^8 \, \text{m/s} \) with a relative magnetic permeability (\( \mu_r \)) of 1, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the relationship between speed, permeability, and permittivity**:
The speed of electromagnetic waves in a medium is given by the formula:
\[
v = \frac{1}{\sqrt{\mu \epsilon}}
...