Consider two converging lenses. The lens on the left has a focal length of 20mm. The second lens, which is placed 65mm to the right of the first lens, has a focal length of 40mm. A small object (height 1.2mm) is placed 90mm to the left of the first lens.

1. Sketch a basic diagram of the situation, including the object, both lenses, and their focal points.

2. Calculate the position and height of the image created by the leftmost lens. Add that image to your diagram. Pay special attention to the location of that image relative to the other items on your diagram.

3. Now calculate the height of the image produced by the rightmost lens. If a person looking into the rightmost lens from the right side, would they be able to see small details in the object? Based on your diagram, what causes this particular effect?

4. Imagine that we move the rightmost lens 1mm to the right. What would a person looking into it from that side see now? Why is this result different from before? The effect you saw in part 3, that the image is both visible and heavily magnified if the object is ever so slightly within the focal length, is a key component of two important optical devices. The one we just looked at is a microscope, magnifying an object that is close by.

5. For a telescope, the object is very, very far away. Using the same lenses as before, where should we place the rightmost lens to get a heavily magnified image of Jupiter?