Thin Lens Formula and Lens Maker Formula NEET Questions

Physics - Optics

Thin Lens Formula and Lens Maker Formula MCQ Questions


7.
In the lens maker's formula, R is taken positive when:
A.
The centre of curvature is on the side of the outgoing (refracted) light
B.
The surface is concave from the source side
C.
The surface is convex from any direction
D.
The centre of curvature is on the side of the incident light
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ANSWER :
A. The centre of curvature is on the side of the outgoing (refracted) light
8.
For a double convex lens with light incident from the left, the signs of R₁ and R₂ are respectively:
A.
Both positive
B.
Positive and negative
C.
Negative and positive
D.
Both negative
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ANSWER :
B. Positive and negative
9.
For a double concave lens with light incident from the left, the signs of R₁ and R₂ are respectively:
A.
Both negative
B.
Both positive
C.
Positive and negative
D.
Negative and positive
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ANSWER :
D. Negative and positive
10.
A double convex lens has both surfaces of equal radius of curvature 20 cm. If n = 1.5, the focal length is:
A.
40 cm
B.
10 cm
C.
20 cm
D.
30 cm
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ANSWER :
C. 20 cm
11.
A plano-convex lens has the curved surface of radius 30 cm and refractive index 1.5. The focal length is:
A.
15 cm
B.
45 cm
C.
60 cm
D.
30 cm
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ANSWER :
C. 60 cm
12.
A plano-concave lens has refractive index 1.5 and the curved surface has radius 20 cm. The focal length is:
A.
-40 cm
B.
+20 cm
C.
-20 cm
D.
+40 cm
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ANSWER :
A. -40 cm