Question

एक उत्तल लेंस की फोकस दूरी 40 सेमी है लेंस की क्षमता गणना कीजिए​

Answer 1

Given:

The focal length of a convex lens is 40 cm

To find:

The power of the lens​

Solution:

We know that,

• The power of the lens denoted as "P" is reciprocal of its focal length denoted as "f" in meters.

• The S.I. unit of power of lens is "dioptres (D)".

• Formula: → $\boxed{\bold{P = \frac{1}{f\:(in\:meters)} }}$

• Power of a convex lens is positive and concave lens is negative.

We will convert the unit of focal length from cm to m

40 cm = $\frac{40}{100}\:m$ = 0.40 m

Now, substituting the value of f in meters in the formula above, we get

$P = \frac{1}{0.40}$

$\implies P = \frac{100}{40}$

$\implies \bold{P = +\:2.5\:D}$

Thus, the power of the convex lens is +2.5 D.

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