Advertisements
Advertisements
प्रश्न
The power of a concave lens is 10 D and that of a convex lens is 6 D. When these two lenses are placed in contact with each other, the power of their combination will be :
(a) +16 D
(b) +4 D
(c) −16 D
(d) −4 D
उत्तर
-4 D
The powers of the lenses add up when brought in contact.
So, net power = +6 D + (-10 D) = -4 D.
APPEARS IN
संबंधित प्रश्न
A small bulb is placed at the focal point of a converging lens. When the bulb is switched on, the lens produces:
(a) a convergent beam of light
(b) a divergent beam of light
(c) a parallel beam of light
(d) a patch of coloured light
Give the position, size and nature of image of formed by a concave lens when the object is placed:
anywhere between optical centre and infinity.
When sunlight is concentrated on a piece of paper by a spherical mirror or lens, then a hole can be burnt in it. For doing this, the paper must be placed at he focus of:
(a) either a convex mirror or convex lens
(b) either a concave mirror or concave lens
(c) either a concave mirror or convex lens
(d) either a convex mirror or concave lens
An object is placed at a distance of 4 cm from a concave lens of focal length 12 cm. Fine the position and nature of the image.
An object is placed on the axis of a lens. An image is formed by refraction in the lens. For all positions of the object on the axis of the lens, the positions of the image are always always between the lens and the object Draw a ray diagram to show it.
Where will the image be formed if an object is kept in front of a concave lens at a distance equal to its focal length? Draw a ray diagram to illustrate your answer.
The power of a lens is negative. State whether it is convex or concave.
The diagrams showing the correct path of the ray after passing through the lens are:
 |
 |
| I | II |
 |
 |
| III | IV |
Draw neat diagram to show the
Divergent action of concave lens
Draw images in case of a concave lens when the object is at infinity.
