A concave mirror forms a real image whose area is 9 times the object area. If the object is 20 cm from the pole, what is |f|?
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A concave mirror forms a real image whose area is 9 times the object area. If the object is 20 cm from the pole, what is |f|?

G1 Physics · Accepted Answer

Area ratio=9 gives |m|=3, so v=60 cm. Then f=uv/(u+v)=20×60/80=15 cm.