Advertisements
Advertisements
Question
Which of the two has a greater power: a lens of short focal length or a lens of large focal length?
Solution
A lens with a shorter focal length will have more power because power varies inversely with focal length .
APPEARS IN
RELATED QUESTIONS
What is meant by a power of a lens? Define its SI unit.
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
Name the physical quantity whose unit is dioptre.
A diverging lens has focal length of 3 cm. Calculate the power.
Fill in the following blank with suitable words :
The reciprocal of the focal length in metres gives you the _________ of the lens, which is measured in ___________.
On reducing the focal length of a lens, its power ______.
Consider three converging lenses L1, L2 and L3 having identical geometrical construction. The index of refraction of L1 and L2 are \[\mu_1 \text{ and } \mu_2\] respectively. The upper half of the lens L3 has a refractive index \[\mu_1\] and the lower half has \[\mu_2\] following figure . A point object O is imaged at O1 by the lens L1 and at O2 by the lens L2placed in same position. If L3 is placed at the same place,
(a) there will be an image at O1
(b) there will be an image at O2.
(c) the only image will form somewhere between O1 and O2
(d) the only image will form away from O2.
The above lens has a focal length of 10 cm. The object of height 2 mm is placed at a distance of 5 cm from the pole. Find the height of the image.
When monochromatic red light is used instead of blue light in a convex lens, its focal length will ______.
The lens of power + 1·0 D is ______.