Question

Ronit focused the image of a candle flame on a white screen using a convex lens. He noted down the
position of the candle , screen and lens as under:
Position of candle from the lens= 24.0 cm
Position of screen from the convex lens = 24.0 cm
i) What is the focal length of the convex lens? 13
ii) Where will the image be formed if he shifts the candle towards the lens at a position of 18 cm?
ii) Draw a ray diagram to show the formation of the image in case (ii) as said above?​

Answer 1

Answer:

( i ) .  Object distance u = 50 - 26 = 24 cm

Image distance v = 74 - 50 = 24 cm .

Since object distance is equal to image distance.

2 f = 24

= > f = 12 cm

So , focal length of object is 12 cm.

( ii ) . u = 50 - 38 = 12 cm

It's mean candle is at focus.

= > Image will form at infinity.

( ii ) Refer to attachment for ray diagram.