Finding the speed of light

For physics class I have been asked to make a experiment to do with optics and waves. For my experiment I have decided to try to find the speed of light!

The current experiment that I am building works like this.

You need a laser, a dremel(something that rotates very very fast), a mirror, a custom bit for the dremel that has a mirror attached to it and a box with a hole through it (this is protect you from shrapnel if the custom bit breaks)

To carry out the experiment you point the laser at the mirror on the dremel and position the second mirror to reflect the laser that comes from the mirror on the dremel back to the mirror. The laser from the dremel should reflect straight back into the laser when everything is properly set up. The dremel bit should be inside to box and the laser shining through the hole in the box.

How the experiment works is that when you turn on the dremel and turn up the power so that it is spinning at about 550 rotations per second or 35000 rpm. When the laser hits the mirror on the dremel it bounces to the second mirror and then back to the mirror on the dremel.

The cool bit is that the dremel has turned very slightly during the time it took to reach the second mirror and bounce back causing the angle that the laser bounces of it at to be different. When you look at the final point the laser reaches, it will now no longer be right back into the laser but slightly off to the side instead.

Using what we know about the difference between where the laser is with the dremel spinning and where it is when it isn’t you can find the speed of light.

Now spinning something at 35000 rpm is very fast. Currently I have been running into problems with the  dremel bits that I have made. The problem is that if they are even slightly unbalanced they create vibrations that ruin results of the experiment and can potentially result in the bit flying apart(which is why you need to have it in the box). Currently the second bit that I have made is looking to be very balance but is also very hard to make. Once that is made the next step for me will be actually carrying out the experiment.

Leave a Reply

Your email address will not be published. Required fields are marked *