Exp. 15 – Geometric Optics
Dear Students,
Please carefully read the instructions given in your lab manual (pages 145-151) about this experiment and follow the outlined procedure (pages 151-155) while watching the lab video from the link given below. Please watch the video in full screen and in full HD (1080p) resolution. Some of the details might be difficult to see on a smaller window and lower resolution. To make it easier to follow the procedure, you will see labels on the video showing which part of the procedure is being performed.
Virtual lab video:
https://www.youtube.com/watch?v=IkxeiO02Vm8
Here are some brief notes on the experimental methods used in these investigations:
Investigations 1 & 2:
In these two investigations, we use the method of ray tracing to trace the path of light rays as they get reflected and refracted. The idea is very simple as you will see from the video. You place a light source that produces a few separate light rays on a piece of paper. These light rays appear as bright lines on the paper. You can trace these lines by simply marking two dots on the paper then later drawing a straight line with a ruler that passes through these dots. If the light rays get reflected or refracted (or changes direction) by optical elements such as a mirror or a lens, you need to repeat this procedure for all the straight portions of the light rays you see on your paper. You can also trace a light ray when it is inside of an optical element such as a lens or an Acrylic trapezoid. All you need to do is to trace the surface of the optical elements and the path of the light rays outside of the optical elements. Then you can draw a line joining the points at which the light ray enters and exits the medium.
For these two investigations, please take screenshots of the results from the video and include them with your lab reports. These also include the measurements you would normally make in a real lab.
Investigation 3:
In this investigation, we form an image on a screen by using a convex lens. The experiment itself is pretty straightforward. You gradually move the screen closer to the object and readjust the position of the lens to get a focused image on the screen. Please follow the video and record the data shown in the video.