Lens Images with an Optics Bench

PIRA 6A60.31

The optics bench shown in the pictures provides a convenient platform for many optics demonstrations.

The lamp shown in the first picture serves well as an object.  The position, separation, and orientation of lenses, object, and screen are easily adjustable.  The scale on the side provides an accurate way to measure distances.  Real images can be projected onto cards mounted on the bench as shown in the last two pictures, or onto a distant screen. Students can look through the lenses to see virtual images.

Another experiment is to cover the center portion of the large lens with the paper disc shown or of a smaller lens with a plastic coin. Students will usually be surprised to see that the entire image is still visible on the screen, only it is dimmer as a portion of the light is blocked. Explaining to the students that the unblocked portion of the lens still focuses light will help students understand how lenses work.