A ball coated with ‘lamp black’ put in a glass tank containing water appears silvery white due to

Options

A. Refraction
B. Diffraction
C. Interference
D. Total internal reflection

Answer

To understand why a ball coated with 'lamp black' appears silvery white when placed in a glass tank containing water, we can break down the explanation into a series of steps:

### Step 1: Understanding the Coating
The ball is coated with 'lamp black', which is a black pigment. This means that the surface of the ball absorbs most of the light that hits it, making it appear black when viewed in isolation.

**Hint:** Consider how colors and surfaces interact with light.

### Step 2: Placing the Ball in Water
When the ball is placed in water, the surrounding medium changes. Water has a different refractive index compared to air. The refractive index of water is higher than that of air, which affects how light behaves when it passes from water to the surface of the ball.

**Hint:** Think about how light travels through different mediums and how it bends at the interface.

### Step 3: Refraction at the Water-Ball Interface
As light travels from the water into the ball, it refracts (bends) due to the change in medium. The ball's surface, being coated with a black pigment, absorbs most of the light, but some light is still reflected back into the water.

**Hint:** Remember the principles of refraction and how they apply at the boundary of two different materials.

### Step 4: Total Internal Reflection
The refractive index of glass is higher than that of water. When light tries to pass from the ball (which is effectively acting like a denser medium due to the lamp black coating) into the water, some of it undergoes total internal reflection. This phenomenon occurs when the angle of incidence exceeds the critical angle.

**Hint:** Recall the conditions for total internal reflection and how it can lead to light being reflected rather than refracted.

### Step 5: Perception of Silvery White Color
The combination of reflected light and the scattering of light in the water creates a visual effect that makes the ball appear silvery white. The light that is reflected back into the water interacts with the water molecules, scattering in such a way that it gives a silvery appearance.

**Hint:** Consider how scattering of light can affect the color perception of an object.

### Conclusion
Thus, the ball appears silvery white due to the effects of refraction, total internal reflection, and light scattering in the water.