When a light ray is incident on a medium of refractive index 4/3, reflected light is found to be 100% polarized. What is the angle of refraction in degrees?
`(tan 53^@ = 4/3)`.

Explanation

To solve the problem, we will use Brewster's law, which states that the angle of incidence (i) at which light is perfectly polarized upon reflection is given by:

\[ \tan(i_p) = n \]

where \( n \) is the refractive index of the medium, and \( i_p \) is the Brewster angle.

### Step-by-Step Solution:

1. **Identify the Refractive Index**:
The refractive index \( n \) of the medium is given as \( \frac{4}{3} \).

2. **Apply Brewster's Law**:
According to Brewster's law:
\[ \tan(i_p) = n = \frac{4}{3} \]

3. **Find the Brewster Angle**:
We know from the problem statement that \( \tan(53^\circ) = \frac{4}{3} \). Therefore, we can conclude that:
\[ i_p = 53^\circ \]

4. **Use the Relationship Between Angles**:
The relationship between the angle of incidence \( i \), angle of refraction \( r \), and the Brewster angle \( i_p \) is given by:
\[ i + r = 90^\circ \]
Hence, we can express the angle of refraction \( r \) as:
\[ r = 90^\circ - i_p \]

5. **Calculate the Angle of Refraction**:
Substituting the value of \( i_p \):
\[ r = 90^\circ - 53^\circ = 37^\circ \]

Thus, the angle of refraction is \( 37^\circ \).

### Final Answer:
The angle of refraction is \( 37^\circ \).