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Standard X

Physics

Dispersion of Light

A parallel be...

Question

A parallel beam of white light falls on a combination of a concave and a convex lens, both of the same material. Their focal lengths are $15 c m$ and $30 c m$ , respectively for the mean wavelength in white light. On the other side of the lens system, one sees colored patterns with violet color at the outer edge.

True

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False

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Solution

The correct option is A True
Net power $= P_{1} + P_{2} = \frac{100}{15} - \frac{100}{30} = \frac{100}{30}$
i.e., the pair act as convex lens of $f = 30$ cm
from fig.,
violet is at the outer edge.

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(IIT-JEE 1985)

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The correct option is A TrueNet power=P1+P2=10015−10030=10030i.e., the pair act as convex lens of f=30cmfrom fig.,violet is at the outer edge.

The correct option is A True
Net power $= P_{1} + P_{2} = \frac{100}{15} - \frac{100}{30} = \frac{100}{30}$
i.e., the pair act as convex lens of $f = 30$ cm
from fig.,
violet is at the outer edge.