I demonstrated chromatic aberration with a glass lens. This is not specifically on the syllabus though.
I also talked briefly about fluorescence (because of the fluorescent dye used in the model eye) - again this is not on the syllabus, but there's a really interesting video here that you might like if you're interested in it.
Homework
Finish June 2015 B and mark using the markscheme I provided.
I showed you a demonstration of a model eye, and we saw the correction of short sight and long sight.
I also showed you an SLR camera, and we went over the silimarities and differences between the eye and the camera.
Homework
I gave out a sheet of key terms you need to know. Watch this video which goes through these key terms, and bring any questions you have to next lesson.
Sight defects & corrections
Classwork
We went over the ray diagrams you did for HW.
You made notes on lens power and we did some example calculations.
We discussed and made notes on laser eye treatment and the use of different materials for spectacle lenses.
You answered Q3 on P119.
Homework
Make notes on the comparision between an eye and a camera using P115 and this video.
Thanks to Mr H there are now lots of past paper questions and answers here if you want to do some.
The Eye
Classwork
We went over the HW questions you did, and especially the conventions for the lens formula: f is positive for converving lenses and negative for diverging lenses; v is positive for real images and negative for virtual images. This was important for Q3 especially.
You did some of the quetsions on P118.
We labelled a diagram of the eye (se P114) and made notes on the function of key parts. If you missed the lesson, this video may help.
We drew two ray diagrams for a normal eye focussing on nearby and distant objects.
Homework
Use P114 to make brief notes on the 'near point', 'far point' and 'range of vision'.
Use P116 and this video to make notes on long and short signtedness, and draw four more eye diagrams for the following situations:
A short sighted person looking at a distant object without a corrective lens
A short sighted person looking at a distant object with a corrective lens
A long sighted person looking at a nearby object without a corrective lens
A long sighted person looking at a nearby object with a corrective lens
We went through the first few questions, but need to go through the rest.
Homework
Answer Q1-3 on P113 using the lens formula and check your answers here.
You may want to watch this video which shows some examples of using the lens formula.
Converging lenses
Classwork
We went over the ray diagrams you did for your HW.
You did a practical with a converging lens to recreate the scenarios from the HW.
We then did ray diagrams for the object exaclty at f, and the object at a distance less than f.
You started the questions on P111 - we will go over these next lesson.
Homework
Draw a ray diagram for a diverging lens. You can watch this video which does lots of examples, but you don't need to watch it all.
Make notes on the lens formula using this video. No need to make notes on magnification again. Make sure you have a clear diagram that labels u and v. We will apply this formula next lesson.
SORRY!!! After posting the video above you pointed out that it uses a different version of the lens formula. We use the version 1/u + 1/v = 1/f.
Very carefully draw the diagrams and make notes on the properties of the image for the first three situations he discusses - up to do between 2f and f.
Answer the questions on P193 and check your answers. It should take about 45 minutes to answer the questions, leaving 20 minutes to mark and correct them.
Homework
Go through what you have done and make a list of things you want to ask me when I get back.
Power & cost of electricity
Classwork
Read and make notes on P186-7.
Answer the questions on P187 and check your answers.
Recap on what we have covered so far, and re-watch any videos if necessary.
Electrical safety, national grid
Classwork
Answer the questions on P181 and check your answers.
Read and make notes on P190-191 (the national grid).
It doesn.t say a lot about transformers . basically at this stage you need to know that they are devices that change the voltage (and current) of AC electricity. A step-up transformer increases the voltage and decreases the current. A step-down transformer does the opposite.
Answer the questions on P191, and check your answers (they will be given to you).
You used an oscilloscope to look at the voltage across a lamp connected to an AC power supply.
You found the amplitude (should have been between 5 and 10V), the period (should have been 0.02s but I expect some variation there) and the frequency (should be 50Hz, but again I expect some variation).
Homework
No homework.
Mains electricity
Classwork
I gave back the test. We will go through it next lesson. If you missed it I gave you a copy - please complete in 30 minutes and hand in to my locker.
We made some notes on mains electricity - mainly on the role of the live, neutral and earth wires.
You wired a plug in pairs - some more successfully than others.
Homework
Make notes on Cables and Plugs using P178-9 and the first six minutes of this video.
Bring your notes to next lesson.
AC & DC
Claswork
We did the test.
We made some notes on AC and DC, and I demonstrated a few things with the slow motion camera, a turntable, and this simulator.
Homework
No homework.
Revision
Classwork
We finished off the past paper questions from last lesson and I gave out the markscheme.
We put some people in the hot seat and asked them lots of questions from this topic.
Homework
Revise for test next lesson.
Force Multipliers
Classwork
You worked through this sheet that introduces concepts about force multiplication.
We made some notes on force multipliers - you need to know that levers and hydraulic systems are force multipliers.
I demonstrated a slightly rubbish hydraulic system made from two syringes, and also showed you a real hydraulic jack.
Next lesson remind me to demonstrate the jack lifting something.
We added to your notes to say that the ratio of the forces in a hydraulic system is equal to the ratio of the piston areas.
Homework
No homework today due to options evening :(
Circular Motion
Classwork
We answered a hard question about the centripetal force on some children on a merry-go-round (see here).
You marked Q2-3 of the HW using the markscheme, and we went through Q1 together.
We plotted the graph from last lesson's practical, and discussed the reults with reference to the formula F=mv²/r (though you don't need to know the formula).
We agreed to do a test on this stuff on Thursday 8th October
We started Q1-3 on P65, but progress on this was very slow so we only went through a small part of it.
We made some notes on stability, and investigated the effect of raising or lowering the centre of mass on stability - though we did not quite finish this.
Homework
First complete these sentences at the end of your notes from today:
If you raise the centre of mass of an object, it becomes ........... stable.
If you lower the centre of mass of an object, it becomes ........... stable.
If you widen the base of an object, it becomes ........... stable.
