Question

11. Aconcave lens of focal length 15 cm forms an image 10 cm from the lens. How far
is the object placed from the lens? Draw the ray diagram.
12. An object is placed at a distance of 16 cm from a convex mirror of focal length
15 cm. Find the position and nature of the image.
13. The magnification produced by a plane mirror is +1. What does this mean?
14. An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex
mirror of radius of curvature 30 cm. Find the position of the image, its nature
and size.
15. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal
length 18 cm. At what distance from the mirror should a screen be placed, so that
a sharp focussed image can be obtained? Find the size and the nature of the image.
16. Find the focal length of a lens of power - 2.0 D. What type of lens is this?
17. A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of
the lens. Is the prescribed lens diverging or converging?
Scien​

Answer 1

Answer:

In this question, we have to calculate the object distance u.

Here, Object distance, u = ? (To be calculated)

Image distance, v = - 10 cm (To the left of concave lens)

And Focal length, f = - 15 cm (It is a concave lens)

Now, putting these values in the lens formula :

1v−1u=1f

We get : −10−1u=1−15

−1u=−115+110

−1u=−2+330

−1u=130

Object distance, u = -30 cm.

Thus, the object is placed at a distance of 30 cm form the concave lens. The minus sign with object distance shows, that the object is on its left side.

Explanation:

Answer 2

Answer:

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