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प्रश्न
State the condition of the following:
A lens has both its focal lengths equal.
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उत्तर
If the medium on both sides of the lens is same, the first and second focal lengths are equal.
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संबंधित प्रश्न
State the condition when a lens is called an equi-convex or equi-concave.
Distinguish between a real and a virtual image.
A ray of light incident at the optical centre of lens, passes undeviated after refraction.
Make the rrect choices in the following items :
An object is placed 50 cm from a connverging lens of focal length 30 cm. The image produced would be
Make the correct choices in the following items :
A lens used as a magnifying glass
(i) ls a diverging lens
(ii) Produces a virtual image
(iii) ls placed with the object nearer the lens than the principle focus
Fig. shows two rays of light Op and OQ coming from an object at the bottom of a pond, incident on the water surface.
(a) Mark on the diagram
(i) The angle of incidence of ray OP,
(ii) The angle of refraction of ray Op,
(iii) The position of image of the object as seen from above.
(iv) An approximate path of the ray OQ.
(b) Explain, why do the rays of light change directions on passing from water to air.
(c) A fish in water sees everything outside the water by rays of light entering its eye in a small cone of light. Draw a diagram and explain how does this happen.
Name the subjective property of light related to its wavelength.
Complete the following diagram and state what happens to the ray of light after refraction through the lens.
Complete the following diagram and state what happens to the ray of light after refraction through the lens.
