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## A lens with f= 10.0 cm is held 45.0 cm from an object. What is the image distance? (Unit = cm) it is not 12 cm.

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## Answers ( )

Answer:1/f = 1/u + 1/v

f=10cm

u=45cm

v=? (Image distance)

1/v = 1/f – 1/u

1/v = 1/10 – 1/45

1/v = (9-2)÷ 90

1/v = 7/90

:. v = 90/7

v=12.86cm(image distance)

Answer:8.2 cm

Explanation:1/f = 1/so + 1/si

1/10 = 1/45 + 1/si

1/si = 1/10 – 1/45

1/si = 9/90 – 2/90

1/si = 7/90

si = 90/7 = 12.86 cm.

since you said that the answer was not 12 them the lens must be concave with negative (minus) focal length

1/f = 1/so + 1/si

– 1/10 = 1/45 + 1/si

1/si = – 1/10 – 1/45

1/si = -9/90 – 2/90

1/si = -11/90

si = -90/11 = – 8.2 cm

– (read: minus or negative sign) indicates the image is in the same side of the object

hope its true and can help you