Advertisements
Advertisements
प्रश्न
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
Advertisements
उत्तर
The sign of power depends on the direction in which a light ray is deviated by the lens. The power could be positive or negative. If a lens deviates a ray towards its centre (converges), the power is positive and if it deviates the ray away from its centre (diverges), the power is negative.
APPEARS IN
संबंधित प्रश्न
What is meant by a power of a lens? Define its SI unit.
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
Which type of lens has a positive power?
A lens has a focal length of, −10 cm. What is the power of the lens and what is its nature?
Express the power (with sign) of a concave lens of focal length 20 cm.
Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see:
(1) a blurred image on the wall of the laboratory.
(2) an erect image of the tree on the lens.
(3) no image as the screen has been removed
(4) an inverted image of the tree at the focus of the lens.
A normal eye is not able to see objects closer than 25 cm because
Which lens has more power a thick lens or a thin lens?
The power of lens depends on the focal length of the lens
Match the following:
| Column - I | Column - II | ||
| 1 | Retina | a | Path way of light |
| 2 | Pupil | b | Far point comes closer |
| 3 | Ciliary muscles | c | near point moves away |
| 4 | Myopia | d | Screen of the eye |
| 5 | Hypermetropia | e | Power of accommodation |
