A glass lens of refractive index 1.5 is placed in a trough of liquid. What must be the refractive index of the liquid in order to make the lens disappear ?

Explanation

To determine the refractive index of the liquid required to make a glass lens of refractive index 1.5 disappear, we can follow these steps:

### Step 1: Understand the Concept of Invisibility
For an object to appear invisible, the light must not refract or reflect when it passes through the object. This occurs when the refractive index of the object is equal to the refractive index of the surrounding medium.

**Hint:** Think about how light behaves when it passes from one medium to another.

### Step 2: Identify the Refractive Indices
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