A magician during a show makes a glass lens with refractive index n = 1.47 disappears in a trough of liquid. What is the refractive index of the liquid ? Could the liquid be water ?

Explanation

To solve the problem, we need to determine the refractive index of the liquid in which the glass lens disappears. The key concept here is that for the lens to become invisible, the refractive index of the liquid must match that of the lens.

### Step-by-Step Solution:

1. **Understanding the Problem**: The magician makes a glass lens with a refractive index (n) of 1.47 disappear in a liquid. For the lens to be invisible, it must not refract light differently than the surrounding liquid.

2. **Condition for Invisibility**: The lens will appear invisible if the refractive index of the liquid (n_liquid) is equal to the refractive index of the lens (n_lens). This is because when the refractive indices are the same, there is no refraction at the interface, and the lens blends into the liquid.

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