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An object is 30.0 cm to the left of a convex lens with a focal length of +8.0 cm. Draw...

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atrinity | Honors

Posted May 27, 2013 at 6:56 PM via web

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An object is 30.0 cm to the left of a convex lens with a focal length of +8.0 cm. Draw a ray diagram of the setup showing the location of the image. Calculate the distance of the image from the lens. Is the image upright or inverted?

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pramodpandey | College Teacher | Valedictorian

Posted May 28, 2013 at 4:32 AM (Answer #1)

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When the an object is placed  beyond the 2f (16) point, the image will always be formed somewhere in between the 2f point and the focal point (f) on the other side of the lens. Regardless of exactly where the object is located, the image will be located in this specified region.The image will be an inverted iamge. That is to say, if the object is right side up, then the image is upside down. In this case, the image is reduced or diminished .

f=8cm

u=-30cm

v= distance of the image

so

`(1/f )= (1/v)-(1/u)`

`(1/8)=(1/v)-(1/(-30))`

`(1/8)-(1/30)=(1/v)`

`v=120/11`

`v=10.91` cm

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atrinity | Honors

Posted May 28, 2013 at 6:06 PM (Reply #1)

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Any chance to get an example ray diagram?

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pramodpandey | College Teacher | Valedictorian

Posted May 29, 2013 at 11:22 AM (Answer #2)

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I have draw ray diagram as follow, you can do the same

A ray parallel to principle axis of lense,through ttop of the object ,after refraction  it will pass through focus f. Another ray through top of the object pass through pole of the lense  ,moves away straight. Where these two rays intersect ,image will formed. If you want can see NCERT -New Delhi Physics book.

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