If the relative permitivity and relative permeability of a medium are 2 and 1.28 respectively, then refractive index of that material is:

Options

A. 1.25
B. 25/16
C. `5/8`
D. `1.6`

Explanation

To find the refractive index of a medium given its relative permittivity and relative permeability, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the given values:**
- Relative permittivity (\( \epsilon_r \)) = 2
- Relative permeability (\( \mu_r \)) = 1.28

2. **Recall the formula for refractive index:**
The refractive index (\( n \)) of a medium can be calculated using the formula:
\[ n = \sqrt{\mu_r \cdot \epsilon_r} \]

3. **Substitute the given values into the formula:**
\[ n = \sqrt{1.28 \cdot 2} \]

4. **Calculate the product inside the square root:**
\[ 1.28 \cdot 2 = 2.56 \]

5. **Take the square root of the product:**
\[ n = \sqrt{2.56} \]

6. **Calculate the square root:**
\[ n = 1.6 \]

7. **Final Answer:**
The refractive index of the material is \( n = 1.6 \).