Nature of project: experimental, data analysis
Available to students on full-time physics degree schemes or joint students.
Rocks which undergo mechanical action such as rubbing together or splitting can create optical luminescence. The effect is generally weak and needs a low light sensitivity camera to see. However there may be occasions when the effect is much brighter, for example occasionally reported earth-quake lights, or glows on the Moon known as Transient Lunar Phenomena. You can try to look for the effect yourself at home before deciding upon this project. Take a sugar cube, switch the lights off, wait about a minute for your eyes to get adapted, then scrape the sugar cube with some metal (e.g. a knife) - you will see the cube flash blue every time the metal scrapes it.
Crushing rocks is a difficult task, which needs specialist equipment. Instead we shall utilize a kitchen blender with some initially soft substances, like sugar cubes, before working your way up onto harder stuff such as a few: mm size chunks of granulated quartz, basalt, flint, granite etc. Doing things in this order will minimize scratches and damage to the blender inside surface until later.
For calibration purposes you will need something like a mercury vapour or sodium lamp to be placed inside the (switched off) blender so as to permit calibration spectra to be taken, and the emission lines of any mechanoluminescence spectra to be determined.
A successful project will develop beyond the above in one/some of the following directions:
1) Try different materials e.g sugar cubes, granulated sugar, salt, basalt, quartz, granite, feldspar etc
2) Try different speed settings of the blender
3) Check the average particle sizes before and after the blending or by stopping the blender, at regular time intevals.
4) How do the light levels change over time?
When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.
Additional scope or challenge if taken as a Year-4 project: Are there any radio frequency emissions produced? Use a radio. There will of course be interference from the blender motor, but you can compare the differences with and without the material inside the blender.
Examine video of the blender experiment in slow motion, frame by frame, and at longer regular intervals to see if there are abrupt changes in light levels when particles collide, or if there is a gradual decrease in brightness over time as the particles become more worn down and eroded.
Please speak to Tony Cook if you consider doing this project.
Initial literature for students:
Average level of difficulty.
|milestone||to be completed by|
|Plan what equipment and materials you will need||end of November|
|Decide upon an experimental procedure to adhere to||Christmas|
|Calibrate the equipment and produce some test spectra||end of February|
|Run set of tests on different types of rocks||mid-March|
Students taking this project will have to submit a full risk assessment form