Question

1. Single convex lenses can be used to make images of far away objects. Will these images be real or imaginary? Where does the image occur relative to the focus? (Specify which side of the lens)

2. Lenses in combination are used in the making of microscopes and telescopes. When observing with the human eye, should the device create real or virtual images? Why?

3. Microscopes often have very bright lights to illuminate the object. If you were to look at the light without the microscope it appears so bright it may "hurt" to look at it. If the microscope magnifies the object to create a larger image, why is it safe to look through microscope at the very bright object? (This is the same concept as why projector bulbs are very bright.)

Please explain in detail, not just with a one sentence answer for each and I will rate. Thank you!

Answer 1

1) The image will be real because it is formed by the actual meeting of the rays converging.

The image is formed at the focal point behind the lens, i.e. on the other side of the lens. This is when the rays coming from the distant object are parallel to the principal axis. Otherwise the image is formed on a line perpendicular and passing through the focal point.

2) When observing with the human eye, the device should create virtual image.

The reason is that when we view an image we want the image to be clear and upright and not inverted. An upright image is formed only when it is virtual.

3) When we look directly, we view it with its original intensity; therefore it may hurt our eyes.

On the other hand when viewing through the microscope the light is reflected a few times and so its intensity decreases, thereby making it safe to view at.