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## Why the focal length of concave lens is negative?

The power of the lens is the reciprocal of the focal length. A concave lens is **a diverging lens**, so it will always have a negative focal length.

## Is focal length of concave negative?

The focal length of a **concave surface is negative**, whereas the focal length of a convex surface is positive. Therefore, for a lens, the power of a concave and convex lens is negative and positive respectively.

## Which lens has more power a thick lens or thin lens?

A **thicker lens** will be having more power because of the focal length of the thicker lens will be less as compared to the thin lens.

## Is V positive for convex lens?

‘**v’ is always positive for convex** mirror & concave lens. Distances measured from the optic center to the right of the lens are considered +ve and t from optic center to the left are -ve.

## Are real images always inverted?

Real image is found when the rays of light converge at a point after reflection on a mirror or after refraction through a lens. … If we placed an object above the x-axis then by geometry the rays will converge below the axis. Therefore, the image formed will be an inverted image. Hence, **a real image is always inverted**.

## How do you tell if an image is real or virtual?

A real image **occurs when light rays actually intersect at the image, and is inverted, or upside down**. A virtual image occurs when light rays do not actually meet at the image. Instead, you “see” the image because your eye projects light rays backward. A virtual image is right side up (upright).

## What is the power of concave lens of focal length 2 cm?

= **-50 dioptres**.

## What is the greatest magnification obtained with a lens of 10cm focal length held 5cm from the eyes take D 25 cm?

Hence, The magnification of convex lens is **3.5**.