A converging lens is kept coaxially in contact with a diverging lens - both the lenses being of equal focal length . What is the focal length of the combination ?

Explanation

To find the focal length of a combination of a converging lens and a diverging lens that are in contact and have equal focal lengths, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Focal Lengths**:
- Let the focal length of the converging lens be \( F \). Since it is a converging lens, we denote it as \( +F \).
- Let the focal length of the diverging lens also be \( F \). Since it is a diverging lens, we denote it as \( -F \).

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