We did a revision quiz which was won by A.M. and did some personal revision.
Revise for mock. Solutions to exam questions in book are here.
We went over the end of topic test.
Revise for mock exam next Thursday.
We did a test on chapters 12 and 13. Results next lesson.
We reched the end of the syllabus and did some circuits questions for fun.
Revise for test on chapters 12 and 13 next Wednesday.
We saw the diffraction pattern produced by a diffraction grating, and calculated the maximum order for a given grating spacing and wavelength.
We used spectroscopes and a spectrometer to observe various emission and absorption spectra.
Answer Q.1-4 on P.207. Check the answers in the back of the book. Hand in tomorrow morning.
Reminder: test next Wednesday.
Single slit pattern
We deduced the wavelength of a laser from the double slit pattern it produced.
We looked at single and double slit diffraction patterns, and the effect of having the slit separation and slit width of a doulbe slit too small in comparison to the distance to the screen.
Watch this video which shows you the pattern produced by a diffraction grating, and read P.205-6 of AQA. Notice how the pattern differs from a double slit pattern.
Watch this video which derives the diffraction grating formula d sinθ = nλ.
Make notes on this and bring any questions you have to next lesson. Next lesson we'll look at the diffraction pattern produced and see some uses for diffraction gratings.
ADVANCE WARNING: there will be a test on chapters 12 and 13 on Weds 19th March.
Double slit interference
We saw the limitations of the fringe spacing formula when D is not greater than s, discussed coherence and the interference patterns produced by monochromatic and white light.
Half the class started to deduce the wavelength of light from a laser using a two slit interference pattern - we will finish this next lesson.
Read p.199-201 and add any extra details to your notes. Bring any questions you have to next lesson.
Answer Q.1,3,4 (NOT 2) on P.201 and hand in tomorrow morning.
Try to make and test the double pinhole the guy talked about in the video from last Wednesday. THERE IS NO NEED TO USE ANYTHING SHARP OR DANGEROUS - just make two dimples in the metal sheet using a biro and sand the dimples until they become small holes.
Two source interference
We observed diffraction of light through one slit and two slits, and interference of sound from two sources.
We covered key terminology (fringe separation, slit separation, etc etc) for Young's double slits, and got a feel for the formula w = λ D / s
Read P.197-8 of the textbook and watch either this video or this video (or both, or any other video you find that is better) and make notes. You do not need to be able to derive the formula w = λ D / s but it is good to see where it comes from.
Answer Q.2-4 on P.198 and check your answers in the back of the book. This basically just involves plugging numbers into the equation above, but take good care with units. Bring your notes and answers to next lesson.
At some point before the next lesson, try to make and test the double pinhole thing the guy talked about in the video from Wednesday. THERE IS NO NEED TO USE ANYTHING SHARP OR DANGEROUS - just make two dimples in the metal sheet using a biro and sand the dimples until they become small holes.
ALSO you may want to have a play around with this refraction and TIR simulation to get a feel for how the critical angle depends on the refractive index of the two materials.
Total internal reflection, interference
We checked results tables and graphs from TIR experiment and discussed coherent bundles of optical fibres.
We looked at a couple of demonstrations of TIR in water streams - hopefully we can improve this next lesson.