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प्रश्न
What is meant by a power of a lens? Define its SI unit.
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उत्तर १
The power of a lens is defined as the reciprocal of its focal length. It is represented by the letter P. The power P of a lens of focal length f is given as
P = 1/f
The SI unit of power is dioptre (D).
उत्तर २
Power of lens: Power of lens is defined as its ability to converge or diverge the rays of light falling on it. SI unit of power is Dioptre.
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संबंधित प्रश्न
Define the power of a lens.
Find the power of a concave lens of focal length 2m.
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens
What can you see in a completely dark room? If you switch on an electric bulb in this dark room as a light source, explain how you could now see:
(a) the electric bulb
(b) a piece of white paper
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
A converging lens has focal length of 50 mm. What is the power of the lens?
A diverging lens has focal length of 3 cm. Calculate the power.
The power of a lens is + 0.2 D. Calculate its focal length.
What do you understand by the power of a lens?
What is the unit of power of a lens? Define the unit of power of a lens.
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be
A pin of length 2.00 cm is placed perpendicular to the principal axis of a converging lens. An inverted image of size 1.00 cm is formed at a distance of 40.0 cm from the pin. Find the focal length of the lens and its distance from the pin.
A convex lens produces a double size real image when an object is placed at a distance of 18 cm from it. Where should the object be placed to produce a triple size real image?
A stick partly immersed in water appears to be bent. Draw a ray diagram to show the bending of the stick when placed in water and viewed obliquely from above.
The power of convex lens of focal length 20 cm is ______.
1 D is equivalent to:
