Advertisements
Advertisements
प्रश्न
The power of a converging lens is 4.5 D and that of a diverging lens is 3 D. The power of this combination of lenses placed close together is :
(a) +1.5D
(b) +7.5D
(c) −7.5D
(d) −1.5D
उत्तर
1.5D
Because power of lens adds up when placed in combination.
Therefore
Net power = 4.5 D + (-3.0 D) = 1.5 D
APPEARS IN
संबंधित प्रश्न
An object 2 cm tall stands on the principal axis of a converging lens of focal length 8 cm. Find the position, nature and size of the image formed if the object is:
(i) 12 cm from the lens
(ii) 6 cm from the lens
State one practical application each of the use of such a lens with the object in position (i) and (ii).
What type of image is always made by a concave lens?
State one practical use each of convex mirror, concave mirror, convex lens and concave lens.
Construct ray diagrams to illustrate the formation of a virtual image using a diverging lens.
What is the difference between the two images formed above?
An object is 2 m from a lens which forms an erect image one-fourth (exactly) the size of the object. Determine the focal length of the lens. What type of lens is this?
What kind of lens is used to correct
short-sightedness
At what distance from a concave lens of focal length 20 cm a 6 cm tall object be placed so as to obtain its image at 15 cm from the lens? Also calculate the size of the image formed.
Draw a ray diagram to justify your answer for the above situation and label it.
Explain the working of an astronomical telescope using refraction of light.
A concave lens has a focal length 30 cm. Find the position and magnification (m) of the image for an object placed in front of it at distance 30 cm. State whether the image is real or virtual?
