a convex lens of focal length 15 cm formed an image 10 cm from the length. how far is the object placed from the lens ? draw the diagram.
don't answer for concave lens.
don't answer for concave lens.
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u=-6
Explanation:
since convex lens produces both real and virtual images,we couldn't tell which one it was producing here. So we assumed that v is positive but that contradicted the constant statement we know that object distance is always negative. We then tried taking v to be negative and got the answer.
note: diagram is not drawn to scale
Answer:
Focal length :- - 15 cm
Image distance V :- - 10 cm
To find:- object distance (u) = ?
Lens formula:- 1 / v - 1 / u = 1 / f
1 / u = 1 / v - 1 / f
1 / u = 1 / - 10 + 1/15
1 / u = - 3 + 2 / 30
1 / u = - 1 / 30
u = - 30 cm
Hemce, the lens is placed 30 cm behind the mirror.