Question

The power of a convex lens of focal length 25 cm is____.
a)+4.0D b)0.25D c)-4.0D d)-0.4D​

Answer 1

Answer:

c.) +4.0D

Explanation:

Given,,

f=+25cm=0.25m

we know,,

Power of lence,

P=1/f(in metre)

=1/0.25

=100/24

=+4.0 D

Hope it'll be helpful to you thanks

Answer 2

Power of lens is +4.0 D (option a)

Given:

• Focal length of convex lens = 25 cm

To find:

• Power of the lens ?

Calculation:

Power of a lens is defined as the ability to converge or diverge light rays.

• Mathematically, power of a lens can be calculated as the reciprocal of focal length (in metres).

• SI unit of power of lens is Dioptres (D).

• Since it is a convex lens, the sign of power will be positive.

$P = \dfrac{1}{f(in \: metres)}$

$\implies P = \dfrac{1}{0.25}$

$\implies P = 4 \: D$

So, option a) is correct✔️