A 80-cm focal length thin lens is placed in contact with one of 59.2 cm focal length.An object is placed 51 cm in front of the combination.What is the image distance?

Question

Quizplus · Accepted Answer

We can use the lens formula 1/f = 1/v - 1/u, where f is the focal length of the lens, v is the image distance and u is the object distance.
For the given combination of lenses, the effective focal length (feff) can be calculated using the formula 1/feff = 1/f1 + 1/f2, where f1 and f2 are the focal lengths of the individual lenses.
1/feff = 1/80 + 1/59.2
feff ≈ 35.29 cm

Now, using the effective focal length and the object distance, we can find the image distance:
1/feff = 1/v - 1/u
1/35.29 = 1/v - 1/51
v ≈ 102 cm

Therefore, the image distance is 102 cm, which corresponds to choice D.

A 80-Cm Focal Length Thin Lens Is Placed in Contact