A concave mirror has focal length 10 cm. An object is 30 cm in front. Where is the image?
Answer and explanation
Correct answer: B. 15 cm in front, from 1/v = 1/10 - 1/30
- Step 1: The mirror equation is 1/f = 1/o + 1/v. Step 2. 1/v = 1/10 - 1/30 = 2/30, so v = 15 cm. Answer: 15 cm in front. Why not the others: Signs and fractions must be combined, not added in the wrong order.
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