The Focal Length of; (i) Convex Mirror (ii) Concave Mirror, and (ii) Convex Lens, Using the Parallax Method NEET Questions

Physics - Experimental Skills

The Focal Length of; (i) Convex Mirror (ii) Concave Mirror, and (ii) Convex Lens, Using the Parallax Method MCQ Questions


13.
The focal length f of a concave mirror is:
A.
Diameter of the mirror
B.
Distance from object to mirror
C.
The distance from the pole P to the principal focus F
D.
Distance from image to mirror
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ANSWER :
C. The distance from the pole P to the principal focus F
14.
The relation between focal length f and radius of curvature R for a spherical mirror is:
A.
f = 2R
B.
f = R²
C.
f = R
D.
f = R/2 (focal length is half the radius of curvature)
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ANSWER :
D. f = R/2 (focal length is half the radius of curvature)
15.
For a concave mirror with R = 30 cm, the focal length is:
A.
15 cm
B.
30 cm
C.
0.5 cm
D.
60 cm
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ANSWER :
A. 15 cm
16.
If the focal length of a concave mirror is 20 cm, the radius of curvature is:
A.
5 cm
B.
40 cm
C.
10 cm
D.
20 cm
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ANSWER :
B. 40 cm
17.
The mirror formula relating object distance u, image distance v, and focal length f is:
A.
1/v - 1/u = 1/f
B.
v × u = f
C.
v + u = f
D.
1/v + 1/u = 1/f
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ANSWER :
D. 1/v + 1/u = 1/f
18.
In the Cartesian sign convention, distances measured AGAINST the direction of incident light are:
A.
Positive
B.
Imaginary
C.
Negative
D.
Always zero
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ANSWER :
C. Negative