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Posts: 3561
12 years ago
John's face is 20 cm in front of a concave shaving mirror. If he observes his image to be twice as big and erect, what is the focal length of the mirror?
A) 10 cm
B) 20 cm
C) 30 cm
D) 40 cm
E) 50 cm
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Valued Member
12 years ago
D
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