A small bulb (assumed to be a point source) is placed at the bottom of a tank containing water to a depth of `80 cm`. Find out the area of the surface of water through which light from the bulb can emerge. Take the value of refractive index of water to be `4//3`.

Explanation

To solve the problem, we need to find the area of the surface of water through which light from a bulb can emerge. The bulb acts as a point source of light at the bottom of a tank filled with water to a depth of 80 cm. We will use the concept of critical angle and the geometry of the situation to find the radius of the circular area of light emerging from the water surface.

### Step-by-Step Solution:

1. **Identify Given Values:**
- Depth of water, \( d = 80 \, \text{cm} = 0.8 \, \text{m} \)
- Refractive index of water, \( \mu = \frac{4}{3} \)

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