Answer:

Yuvraj focused the image of a candle on a white screen using a convex lens. He noted down the position of a candle screen and the lens as given below. As the object is brought closer to the convex lens from infinity to focus, the image moves away from the convex lens from focus to infinity. Also the size of image goes on increasing and the image is always real and inverted. A concave lens always gives a virtual, erect and diminished image irrespective to the position of the object.

Position of the candle = 12 cm

Position of the convex lens - 50 cm

Position of the screen = 88 cm.

Answer the following questions:

(i) What is the focal length of the convex lens?

(a) f= + 15 cm

(b) f= - 15 cm

(c) f= + 19 cm

(d) f = - 19 cm

(ii) Where will the image be formed if he shifts the candle towards the lens at a position of 31 cm.

(a) v = + 25 cm

(b) v = -25 cm

(c) v = 0

(d) v = infinity

(iii) What will be the nature of the image formed if he shifts the candle towards the lens?

(a) Virtual & erect, diminished

(c)Real & Inverted, diminished

(b) Virtual & erect, enlarged

(d) Real& Inverted, enlarged

(iv)The size of image formed by a convex lens when the object is placed at the Focus of convex lens is

(a)highly enlarged

(b) infinity

(c) highly diminished

(d) same as that of object