What is the focal length of a concave mirror if the object is placed at a distance of 30 cm and the image is formed at a distance of 15 cm from the mirror? (2021)
Practice Questions
1 question
Q1
What is the focal length of a concave mirror if the object is placed at a distance of 30 cm and the image is formed at a distance of 15 cm from the mirror? (2021)
10 cm
15 cm
20 cm
25 cm
Using the mirror formula, 1/f = 1/v + 1/u. Here, v = -15 cm (image distance is negative for concave mirror) and u = -30 cm. Therefore, 1/f = 1/(-15) + 1/(-30) = -1/10. Thus, f = 10 cm.
Questions & Step-by-step Solutions
1 item
Q
Q: What is the focal length of a concave mirror if the object is placed at a distance of 30 cm and the image is formed at a distance of 15 cm from the mirror? (2021)
Solution: Using the mirror formula, 1/f = 1/v + 1/u. Here, v = -15 cm (image distance is negative for concave mirror) and u = -30 cm. Therefore, 1/f = 1/(-15) + 1/(-30) = -1/10. Thus, f = 10 cm.
