Question

17.A 2.0 cm long pin is placed perpendicular to the principal axis of a convex lens of focal length 12cm. the distance of the pin from the lens is 15cm. find the size of the image.

(4 Points)

2cm

4cm

6cm

8cm​

Answer 1

Answer:

Here, u = -15cm, f= 12cm, h1= 2cm, v=?, h2=?

Using lens formula,

1/f = 1/v - 1/u

=> 1/v = 1/f + 1/u

=> 1/v = 1/12 + 1/(-15)

=> 1/v = 1/60

=> v = 60cm which indicates that the image formed is real and inverted.

Now magnification = v/u = h2/h1

Hence, 60/(-15) = h2/2

=> h2 = -8cm

-ve sign indicates inverted image. Hence, the size of the image is 8cm.

Answer 2

Answer:

8cm

Explanation:

first we have to find v so we use begger formula

1/f=1/u - 1/v

1/v= 1/12 - 1/15 = v=60

m= -v/u

m=-60/-15

m=4

m=h2/h1 = 4=h2/2

h2= 8cm