If a combination of 3 convex lens is arranged in the shown manner the focal length of lens 1 is $+ 5 c m$ , lens II is $10 c m$ and lens III is $20 c m$ . Calculate the total power of the combination of the lens.

- 0.35 D

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+ 0.1 D

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+ 0.35 D

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+ 0.75 D

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Solution

The correct option is C $+ 0.35 D$
Total power is the sum of individual powers.
$P = P_{1}$ + $P_{2}$ + $P_{3}$

Also, power is equal to the inverse of focal length.
$P = \frac{1}{5} + \frac{1}{10} + \frac{1}{20}$
$P = \frac{7}{20}$
$P = + 0.35 D$

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Similar questions

If a combination of 3 convex lens is arranged in the shown manner the focal length of lens I is + 10 cm, lens II is 20 cm and lens III is 40 cm. Calculate the total power of the combination of lens?

A combination of $3$ convex lenses is made. The focal length of lens I is $+ 5 c m$ , lens II is $+ 10 c m$ and lens III is $+ 20 c m$ . Calculate the total power of the combination in dioptre?

Q. The focal length of lens I is

+ 5 c m

, lens II is

+ 10 c m

and lens III is

+ 20 c m

. The total power of the combination of the lens is.

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If a combination of 3 convex lens is arranged in the shown manner the focal length of lens 1 is +5 cm, lens II is 10 cm and lens III is 20 cm. Calculate the total power of the combination of the lens.

The correct option is C +0.35 DTotal power is the sum of individual powers. P=P1 + P2 + P3 Also, power is equal to the inverse of focal length. P=15+110+120 P=720 P=+0.35 D

If a combination of 3 convex lens is arranged in the shown manner the focal length of lens 1 is $+ 5 c m$ , lens II is $10 c m$ and lens III is $20 c m$ . Calculate the total power of the combination of the lens.

The correct option is C $+ 0.35 D$
Total power is the sum of individual powers.
$P = P_{1}$ + $P_{2}$ + $P_{3}$

Also, power is equal to the inverse of focal length.
$P = \frac{1}{5} + \frac{1}{10} + \frac{1}{20}$
$P = \frac{7}{20}$
$P = + 0.35 D$