A lens forms a real image of an object placed at a distance of 60 cm from it. If the image distance is 15 cm, what is the focal length of the lens?
Practice Questions
1 question
Q1
A lens forms a real image of an object placed at a distance of 60 cm from it. If the image distance is 15 cm, what is the focal length of the lens?
10 cm
12 cm
20 cm
25 cm
Using the lens formula 1/f = 1/v - 1/u, we have 1/f = 1/15 - 1/60. Solving gives f = 10 cm.
Questions & Step-by-step Solutions
1 item
Q
Q: A lens forms a real image of an object placed at a distance of 60 cm from it. If the image distance is 15 cm, what is the focal length of the lens?
Solution: Using the lens formula 1/f = 1/v - 1/u, we have 1/f = 1/15 - 1/60. Solving gives f = 10 cm.
Steps: 7
Step 1: Identify the given values. The object distance (u) is -60 cm (negative because it is on the same side as the object) and the image distance (v) is 15 cm.
Step 2: Write down the lens formula: 1/f = 1/v - 1/u.
Step 3: Substitute the values into the lens formula: 1/f = 1/15 - 1/(-60).
Step 4: Calculate 1/15, which is 0.0667, and 1/(-60), which is -0.0167.
