Question: What is the focal length of a converging lens if it forms a real image at a distance of 30 cm from the lens when the object is placed at 60 cm?
Options:
Correct Answer: 20 cm
Solution:
Using the lens formula (1/f = 1/v - 1/u), we find f = 1/(1/30 - 1/60) = 20 cm.
