Question

A 2 cm long pin is placed perpendicular to the principal axis of a convex lens of focal length 15 cm the distance of 25 cm from the lens find the position of image and its size.​

Answer 1

Answer:

Height of the object, h1=6cm

Focal length of the concave mirror, f=−5cm

Position of the image, v=? Size of the image , h2=?

Object distance , u=−10cm

According to lens formula:

1v−1u=1f⇒1v−1−10=1−5⇒1v+110=−15

⇒1v=−15−110=−2−110=−310∴v=−103=−3.3cm

h2h1=vu⇒h26=−103−10

⇒h26=103×10=13⇒h2=63∴h2=+2cm

Thus the image is formed at a distance of 3.3 cm from the concave lens. The negative (-) sign for image distance shows that the image is formed on the left side of the concave lens (i.e., virtual). The size of the image is 2 cm and the positive (+) sign for hand image shows that the image is erect.

Thus a virtual, erect, diminished image is formed on the same side of the object (i.e., left side).