# What Is the Focal Length of the Concave Lens in This Lens-Mirror Combination?

• avalanche007
In summary, a convex lens forms a real image of a point object at a distance of 50 cm from the lens. When a concave lens is placed 10 cm behind the convex lens on the image side, the final image coincides with the object after placing a plane mirror on the image side and facing the concave lens. To find the focal length of the concave lens, use the equation 1/f = 1/v - 1/u, where v is +50 cm for the convex lens as the real image is formed on the opposite side of the object. This image then acts as the object for the concave lens. Further steps are unable to be determined without drawing a ray diagram.
avalanche007

## Homework Statement

a convex lens forms a real image of a point object at a distance of 50 cm from convex lens. a concave lens is placed 10 cm behind convex lens on image side. on placing a plane mirror on the image side and facing the concave lens it is observed that final image now coincides with the object itself. find focal length of concave lens.

1/f = 1/v - 1/u

## The Attempt at a Solution

v= +50cm for convex lens as real image is formed on opposite side to object.
this acts as object for concave lens
unable to proceed further

Try drawing a ray diagram.

## What is a combination of lens and mirror?

A combination of lens and mirror is a set-up in which a lens and a mirror are used together to manipulate light. This can result in various optical effects and can be used in different scientific experiments and devices.

## What are some examples of devices that use a combination of lens and mirror?

Some examples of devices that use a combination of lens and mirror include telescopes, microscopes, cameras, and projectors. These devices use the lens to focus the light and the mirror to reflect and redirect the light in a specific direction.

## How does a combination of lens and mirror affect the quality of an image?

A combination of lens and mirror can improve the quality of an image by correcting any distortions or aberrations caused by the lens alone. The mirror can also help in magnifying or reducing the size of the image, depending on its position in the set-up.

## What is the difference between using a single lens and a combination of lens and mirror?

Using a single lens can result in some distortions or aberrations in the image, while a combination of lens and mirror can correct these issues. Additionally, a combination of lens and mirror can also provide a wider field of view and better control over the direction of the light.

## What are the advantages of using a combination of lens and mirror in scientific experiments?

Using a combination of lens and mirror can provide more flexibility and control in manipulating light, leading to more accurate and precise results in experiments. It also allows for a wider range of optical effects to be achieved, making it a useful tool in various scientific fields.

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