Anonymous asked in Science & MathematicsPhysics · 1 year ago

Did my science teacher make a typo or is there actually way to answer it?

On the worksheet my teacher put in the following question " An object is placed 24cm in front of converging lens. The focal length is 8 cm. Find the location and height of image". I found the distance of image but can't seem to find a way to find the height of image without height of object. Is it just my dumb brain that can't solve it or my teacher forgot to put the height of the object in?

1 Answer

  • 1 year ago

    Your teacher made a mistake/omission. My answer would be:

    1/u + 1/v = 1/f (assuming you are using these symbols)

    1/24 + 1/v = 1/8

    1/v = 1/8 - 1/24 = (3 - 1)/24 = 1/12

    v = 12cm (image distance)

    Magnification = -v/u = -12/24 = -0.5

    No object height is given in the question. If we call the height of the object h cm, then the image height is -0.5h cm. This means the image is half the size of the object; the negative sign tells us the image is inverted.

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