Wave Optics Test

Result

Wave Optics Test - 9

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Weekly Quiz Competition

Question 1
1 / -0

For the given statements of assertion and reason, mark the correct answer as follows:
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If both assertion and reason are false.
Assertion: A biconvex lens of focal length 10 cm is split into two equal parts by a plane parallel to its principal axis. The focal length of each part will be 20 cm.
Reason: Focal length does not depend on radii of curvature of two surfaces.

A
(a)

B
(b)

C
(c)

D
(d)

Solution

When lens is split parallel to principle axis ,it will not change focal length of lens,it will change in amount of light entering in each part.So assertion is wrong.Focal length depends on radius of curvature,thus reason is also false.
Question 2
1 / -0

A bird in air looks at a fish vertically below it inside water. X is height of the bird above the surface of water, and Y is depth of the fish below the surface of water. If the refractive index of water with respect to air is μ, the distance of the fish as observed by the bird is

A
X + Y

B
X + (Y/μ)

C
μX + Y

D
μX+μY

Solution

True Depth/Apparent Depth = μ
Apparent Depth = Y/μ
As bird is at a height X, the distance of the fish as observed by the bird is X + Y/μ.
Question 3
1 / -0

A microscope is focused on a mark on a piece of paper. A slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again?

A
1 cm upward

B
4.5 cm downward

C
1 cm downward

D
2 cm upward

Solution

Apparent depth of the mark = 3/1.5 = 2 cm
This means the mark has apparently moved up by 1 cm. The apparent distance of the mark is 2 cm. So, the microscope has to be moved upward by 1 cm.