Post-UTME Physics 2017 Objective — Question 11
Question 11 of 20 from the Post-UTME Screening (Post-UTME) Physics 2017 Objective paper, with the correct answer and a full explanation.
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An object is placed at a distance of 20cm in front of a concave mirror. If the magnification is I (unity), what is the focal length of the mirror?
- A. 20cm
- B. 10cmCorrect
- C. 5cm
- D. 1cm
Explanation
For unit magnification with a real, inverted image, the object is at the centre of curvature (u=2f=20cm), giving f=10cm.
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