Thin Lens Formula and Lens Maker Formula NEET Questions

Thin Lens Formula and Lens Maker Formula

Thin Lens Formula and Lens Maker Formula MCQ Questions

1.
The thin lens formula is given by:
A.
1/v - 1/u = 1/f
B.
1/u - 1/v = 1/f
C.
1/v + 1/u = 1/f
D.
v - u = f
ANSWER :
A. 1/v - 1/u = 1/f
2.
The thin lens formula is valid for:
A.
Only convex lenses with real images
B.
Both convex and concave lenses, for both real and virtual images
C.
Only concave lenses
D.
Only paraxial rays from a point source on axis
ANSWER :
B. Both convex and concave lenses, for both real and virtual images
3.
In the lens formula 1/v - 1/u = 1/f, the sign convention takes:
A.
Image distance v always negative
B.
Object distance u always positive
C.
All distances from the optical centre as positive
D.
Distances measured along the direction of incident light as positive, against it as negative
ANSWER :
D. Distances measured along the direction of incident light as positive, against it as negative
4.
For a real object placed in front of a convex lens, the object distance u is:
A.
Always equal to focal length
B.
Positive
C.
Zero
D.
Negative
ANSWER :
D. Negative
5.
The lens maker's formula for a thin lens in air is:
A.
1/f = n(1/R₁ - 1/R₂)
B.
1/f = (n + 1)(1/R₁ + 1/R₂)
C.
1/f = (n - 1)(1/R₁ - 1/R₂)
D.
1/f = (n - 1)(1/R₁ + 1/R₂)
ANSWER :
C. 1/f = (n - 1)(1/R₁ - 1/R₂)
6.
The lens maker's formula when the lens (refractive index n₂) is placed in a medium of refractive index n₁ is:
A.
1/f = (n₁ - n₂)(1/R₁ + 1/R₂)
B.
1/f = (n₁/n₂ - 1)(1/R₁ - 1/R₂)
C.
1/f = (n₂/n₁ - 1)(1/R₁ - 1/R₂)
D.
1/f = (n₂ - n₁)(1/R₁ - 1/R₂)
ANSWER :
C. 1/f = (n₂/n₁ - 1)(1/R₁ - 1/R₂)