A 4.0-cm object is placed 30.0 cm from a converging lens that has a focal length of 10.0 cm as shown in the diagram.
Note: The diagram is not drawn to scale.

-A second converging lens is placed 20.0 cm to the right of the lens shown in the figure.Determine the focal length of the second lens if an inverted image (relative to the object in the diagram)is formed 13.3 cm to the right of the first lens.
A)1.33 cm
B)6.67 cm
C)13.3 cm
D)15.4 cm
E)19.7 cm

Question

A 4.0-cm object is placed 30.0 cm from a converging lens that has a focal length of 10.0 cm as shown in the diagram.
Note: The diagram is not drawn to scale.
 
-A second converging lens is placed 20.0 cm to the right of the lens shown in the figure.Determine the focal length of the second lens if an inverted image (relative to the object in the diagram)is formed 13.3 cm to the right of the first lens.
A)1.33 cm 
B)6.67 cm 
C)13.3 cm 
D)15.4 cm 
E)19.7 cm

Quizplus · Accepted Answer

Given that the image formed by the first lens is 13.3 cm to the right of it, this image acts as the object for the second lens. Since the second lens is placed 20.0 cm to the right of the first lens, the object distance for the second lens is -6.7 cm (negative because the object is on the same side as the incoming light). The image distance (v) for the second lens is given as the distance from the first lens to the final image position, which is 13.3 cm. To find the focal length (f) of the second lens, we use the lens equation: 1/f = 1/v - 1/u. Substituting v = 13.3 cm and u = -6.7 cm, we solve for f, which gives us approximately 19.7 cm.

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