Two thin converging lens of focal lengths 15 cm and 30 cm respectively are held in contact with each other. Calculate power and focal length of the combination.

Explanation

To solve the problem of finding the power and focal length of the combination of two converging lenses, we will follow these steps:

### Step 1: Identify the focal lengths of the lenses
Let:
- \( f_1 = 15 \, \text{cm} \) (focal length of the first lens)
- \( f_2 = 30 \, \text{cm} \) (focal length of the second lens)

### Step 2: Use the lens formula for combined focal length
...