Teaching Notes

If students have difficulty finding an image, give them a file card and suggest that they locate the real image made by the objective. For them to see this image of an object outside, the room will have to be darkened. Point out that the eyepiece is magnifying this image, so the image must be just inside the focal length of the eyepiece. With the telescope trained on a distant object, have them move the eyepiece back and forth until they see the image. You may have to mention that if the lenses are spaced to focus on a distant object, they may not make a sharp image of an object in the classroom.

SAFETY PRECAUTION: Students are never to look at the Sun.