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## What is the power of lens of focal length 20 cm?

The power of a lens of focal length 20cm is **5D**.

So both lenses have same convergence of refracted light. The diopter is the unit of measure for the refractive power of a lens.

## What is the power of a convex lens if its focal length is 20 cm?

p = 1/f=1/20=100/20=**5 diopter**.

## What is the power of a concave lens of focal length?

The power of the lens is the reciprocal of the focal length of the lens. We know that, The focal length is the negative for the concave lens. Hence, The power of the concave lens is **-0.5 D**.

## What is the focal length of 20cm?

**A concave lens** has a focal length of 20 cm.

## What is the Power of concave lens of focal length 2m?

Thus, the power of this concave lens is, **-0.5 dioptre**.

## How do you calculate the power of a convex lens?

The power of a lens is defined as the reciprocal of its focal length in meters, or **D = 1/f**, where D is the power in diopters and f is the focal length in meters.

## What is the power of convex lens of focal length 50 cm?

= 100/50 = **2 dioptre**. The SI unit of power is dioptre.

## What is the magnifying power of a concave lens?

The image formed by a concave mirror is always smaller than the size of the object. Therefore, the magnification of a concave mirror is **always less than 1**.

## What is the power of a concave lens of focal length 4 m *?

So, the power of the lens is **0.25 D**.

## How do you find the power of a concave lens?

**Answer**

- Given that, Focal length of the concave lens, f = 2 m.
- To find, Power of the lens.
- Solution, The relation between power and focal length of the lens is inverse. Power is given by : P = 1/f.
- f is the focal length of the lens and it is negative for concave lens.

## What would be the power of concave lens which has a focal length of 0.5 m?

Answer: In the same way, a power of **-2.0D** means a concave lens of focal length -0.5m.