Power of a Lens
Trending Questions
Q.
A combination of 3 convex lenses is arranged as shown. The focal length of lens I is +5 cm, lens II is +10 cm and lens III is +20 cm. Calculate the total power of the combination of the lens?
- + 35 D
- + 75 D
- -35 D
- +1 D
Q. What is the nature of the image formed by a convex lens if the magnification produced by the lens is +3?
a) Virtual and diminished
b) Real and erect
c) Real and diminished
d) Virtual and magnified
[1 Mark]
a) Virtual and diminished
b) Real and erect
c) Real and diminished
d) Virtual and magnified
[1 Mark]
Q.
If lens A has focal length +15 cm and lens B has focal length +30 cm, find out which lens has more power?
Lens B has more power
Lens A has more power
Power of the lens cannot be determined
Both have the same power
Q.
Convex lens of focal length 15 cm is kept in series with a concave lens of focal length 30 cm. Find the power of the combination of lenses?
3.33 D
+ 0.033 D
- 0.6 D
+ 0.6 D
Q. Two thin lenses of focal lengths f1 and f2 are placed in contact with each other. The focal length of the combination will be given by:
- f1f2f1−f2
- √f1f2
f1f2f1+f2
f1+f22
Q.
Negative power indicates that it is a ___.
concave lens
convex lens
combination two convex lenses
- combination three convex lenses
Q. If f is the focal length of the lens, then the power of a lens is equal to
- 100f(cm)
- 10f(cm)
- 1100 f(cm)
- 100f(m)
Q. The power of three lenses A, B, and C are 1, 2 and 3 dioptre respectively. What is the power of the combination of these lenses?
- 2 dioptre
- 6 dioptre
- 9 dioptre
- 3 dioptre
Q. The magnification produced by a plane mirror is ___ .
- 2
- infinite
- 1
- 0
Q. Power of a convex lens of focal length 50 cm is ___.
- -2D
- -0.5D
- +2D
- +0.5D