A person cannot see distincly any object placed beyond 40cm from his eye. The power of the lens which will enable him to see distant stars clearly is.

Explanation

To solve the problem, we need to determine the power of the lens required for a person who cannot see distinctly beyond 40 cm. Here's a step-by-step solution:

### Step 1: Understand the Problem
The person has a far point of 40 cm, meaning he can only see objects clearly up to this distance. To see distant objects (like stars), we need to create a virtual image of these objects at his far point.

### Step 2: Define the Parameters
- The far point (D) of the person = 40 cm = 0.4 m.
- The object distance (u) for distant objects (like stars) is considered to be at infinity (u = -∞).
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