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.

Question

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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Thành Đạt 6 months 2021-08-26T10:08:42+00:00 2 Answers 5 views 0

Answers ( )

  1. linhdan
    0
    2021-08-26T10:09:42+00:00
    Reply

    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)

  2. diemkieu
    0
    2021-08-26T10:10:38+00:00
    Reply

    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

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