Question

. You are given three medium X, Y, Z .The refractive index of the three medium are n1 , n2 and n3. It is given that n1 > n3 > n2 . In which of these does the light travel fastest?(1)
7. What do you mean by power of the lens? What is the power of a concave lens of focal length 10 cm? (2)

8. A concave lens of focal length 15 cm forms an image of 10 cm from the lens. (2)
a) How far is object from the lens?
b) What is the power of the lens?
2 / 2


9. 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. (2)
10. Why does the sun appear reddish early in the morning ? (3)

​

Answer 1

Answer:

. You are given three medium X, Y, Z .The refractive index of the three medium are n1 , n2 and n3. It is given that n1 > n3 > n2 . In which of these does the light travel fastest?(1)

7. What do you mean by power of the lens? What is the power of a concave lens of focal length 10 cm? (2)

8. A concave lens of focal length 15 cm forms an image of 10 cm from the lens. (2)

a) How far is object from the lens?

b) What is the power of the lens?

2 / 2

9. 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. (2)

10. Why does the sun appear reddish early in the morning ? (3)