Two lenses are placed at a distance of f1 - f2. What is the focal length of the combination?
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It depends on the distance between them. If their distance is d and the focal lengths of the lenses are f1 and f2, then the focal length f of the combined system is determined by
1/f = 1/f1 + 1/f2 − d/f1f2.
The thickness of each lens is neglected here.
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ANSWER IS HERE
Consider two thin lens f1 and f2 of focal length f1and f2 held coaxially in contact with each other. Let P be the point where the optical centres of the lenses coincide (lenses being thin).
It always depends on the distance between them. If the possible numerical value of their distance is d and the focal lengths of the lenses areof the values f1 and f2, then the focal length f of the combined system is determined by this formula.
1/f = 1/f1 + 1/f2 − d/f1f2.
The thickness of each lens is is so small that they have to be neglected.
the formula for the effective focal length of two thin lenses with focal lengths f1f1and f2f2 separated by distance d to be
1f=1f1+1f2−df1f2.
HOPE IT HELPS YOU
BRAINLIEST ANSWER
Consider two thin lens f1 and f2 of focal length f1and f2 held coaxially in contact with each other. Let P be the point where the optical centres of the lenses coincide (lenses being thin).
It always depends on the distance between them. If the possible numerical value of their distance is d and the focal lengths of the lenses areof the values f1 and f2, then the focal length f of the combined system is determined by this formula.
1/f = 1/f1 + 1/f2 − d/f1f2.
The thickness of each lens is is so small that they have to be neglected.
the formula for the effective focal length of two thin lenses with focal lengths f1f1and f2f2 separated by distance d to be
1f=1f1+1f2−df1f2.
HOPE IT HELPS YOU
BRAINLIEST ANSWER
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