Question

A student uses a lens of focal length 40 cm and another of (-
20) cm. Write the nature and power of each lens.

Answer 1

Answer:

Quit

Explanation:

Question Incomplete

Answer 2

Answer:

• Negative means virtual image
• positive meaning real image
• Virtual image is produced by concave lens
• Real image is produced by convex lens

From the above points we can tell that first lens is convex lens as there is + sign and second lens is concave lens as it has - sign.

$power \: of \: lens \: = \frac{1}{focal \: length}$

Focal length is the point where refracted ray of lens converge.

Unit if power is dipotres(D)

Power of first lens is 1/40 D

power of 2nd lens is 1/-20 D