Assertion A ray of light travels from first medium to second medium. In first medium, angle of ray with normal is `i_(1) =30^(@)` and in second medium `i_(2)` = `60^(@)` Then, second medium is rarer medium.

Options

A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

To determine whether the second medium is rarer than the first medium based on the given angles of incidence, we can use Snell's Law, which states:

\[ \mu_1 \sin(i_1) = \mu_2 \sin(i_2) \]

where:
- \(\mu_1\) is the refractive index of the first medium,
- \(\mu_2\) is the refractive index of the second medium,
- \(i_1\) is the angle of incidence in the first medium,
- \(i_2\) is the angle of refraction in the second medium.

### Step-by-Step Solution:

1. **Identify the Given Values**:
- Angle of incidence in the first medium, \(i_1 = 30^\circ\)
- Angle of refraction in the second medium, \(i_2 = 60^\circ\)

2. **Calculate the Sine Values**:
- \(\sin(i_1) = \sin(30^\circ) = \frac{1}{2}\)
- \(\sin(i_2) = \sin(60^\circ) = \frac{\sqrt{3}}{2}\)

3. **Apply Snell's Law**:
\[ \mu_1 \sin(30^\circ) = \mu_2 \sin(60^\circ) \]
Substituting the sine values:
\[ \mu_1 \cdot \frac{1}{2} = \mu_2 \cdot \frac{\sqrt{3}}{2} \]

4. **Rearranging the Equation**:
\[ \frac{\mu_1}{\mu_2} = \frac{\sqrt{3}}{1} \]
This implies:
\[ \mu_1 = \sqrt{3} \cdot \mu_2 \]

5. **Interpret the Result**:
Since \(\mu_1 > \mu_2\), it indicates that the first medium is denser than the second medium. Therefore, the second medium must be the rarer medium.

### Conclusion:
The assertion that the second medium is rarer is true.