Physics, asked by SayorDutta, 5 months ago

3. A converging lens of 4 dioptre and a diverging lens of 3 dioptre are
combined together. What is the focal length of the combination?

Answers

Answered by TheVenomGirl

AnswEr :

$\\$

We're given that, a converging lens and diverging lens with some Power. And we've to find out the focal length of the combination.

$\\$

$\\$

$\\$

We know that, for any combination of lens, the power is added taking +ve/-ve sign. Also, power is reciprocal of focal length. So,

$\\$

$\sf \longrightarrow \: \: P_{combination} = P_1 + P_2 \\ \\$

$\sf \longrightarrow \: \: P_{combination} = 4 + 3 \\ \\$

$\sf \longrightarrow \: \: \blue{P_{combination} = 7} \\ \\$

Now, we know that, power is reciprocal of focal length. So,

$\\$

$\sf \longrightarrow \: \: f = \dfrac{1}{P} \\ \\$

$\sf \longrightarrow \: \: f = \dfrac{1}{7} \\ \\$

$\sf \longrightarrow \: \: f = 0.7 \: m \\ \\$

$\sf \longrightarrow \: \: \green{ f = 70 \: cm} \\ \\$

Therefore, focal length of the combination is 70 cm .

Previous Question

Next Question