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.

– 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 = $P_{|}$ + $P_{| |}$ + $P_{| | |}$ ; P = $\frac{1}{f}$
$P_{|}$ = $\frac{1}{5}$ D ; $P_{| |}$ = $\frac{1}{10}$ D ; $P_{| | |}$ = $\frac{1}{20}$ D
Total (P) = $\frac{1}{5}$ + $\frac{1}{10}$ + $\frac{1}{20}$ = $\frac{7}{20}$
P = + 0.35 D

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Similar questions

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.

Q. A convex lens of focal length

20 c m

is placed in contact with a concave lens of focal length

10 c m .

calculate power of combination.

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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 D Total Power = P| + P|| + P||| ; P = 1f P| = 15 D ; P|| = 110 D ; P||| = 120 D Total (P) = 15 + 110 + 120 = 720 P = + 0.35 D

The correct option is C
+ 0.35 D

Total Power = $P_{|}$ + $P_{| |}$ + $P_{| | |}$ ; P = $\frac{1}{f}$
$P_{|}$ = $\frac{1}{5}$ D ; $P_{| |}$ = $\frac{1}{10}$ D ; $P_{| | |}$ = $\frac{1}{20}$ D
Total (P) = $\frac{1}{5}$ + $\frac{1}{10}$ + $\frac{1}{20}$ = $\frac{7}{20}$
P = + 0.35 D