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