Question

4. The refractive index of medium a is 1.74 and and that of another medium bis 2.36 , in which medium ,a or b
, the speed of light is more?
5. Find the power of a concave lens of focal length 120 cm.

6. Two lenses of power +5.0 D and -7.5 D are kept in contact with each other. Find the power and focal length of
this lens combination.

7. The focal length of a diverging lens is 15 cm ,at what distance should an object be placed from this lens so that it
forms an image at 10 cm from lens ?Also calculate the magnification what is the nature of the image formed ?

8. A convex lens produces an inverted image magnified three times of an object placed at a distance of 15 cm from
it.Calculate focal length of the lens.
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Answer 1

Answer:

for 4th Question the answer of in medium A because it has less optical density to that of medium B having an optical density of 2.36