## Question

The equi-convex lens, shown in the figure, has a focal length *f*. What will be the focal length of each half if the lens it cut along *AB*? (See fig.)

### Solution

2*f*

For equi-convex lens *R*_{1} = –*R*_{2}, so that

If the lens is cut along *AB*, we have two plano convex lenses. For a plano convex lens, *R*_{2} = ∞. Therefore, its focal length *f’* is

#### SIMILAR QUESTIONS

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