Welcome back to Physics. I hope you had a splendid holiday.
We looked at the newe topic of waves. Waves transfer energy from one place to another without there being any overall movement of matter. They require a medium (material) to travel through.
In transverse waves, vibrations in the medium are at right angles to the direction that the wave is travelling in.
In longitudunal waves, the vibrations of the medium are in the same direction as the direction that the wave is travelling in.
All waves will reflect off a plane surface with an angle of incidience which is equal to the angle of reflection. All waves will spread out (diffract) when they pass through a gap which is a simlilar size to the wavelength of the wave. All waves will change direction (refract) if they pass through into a different medium which causes them to change speed.
The wave equation:
Wavespeed = Frequency times Wavelength
Frequency = Number of vibrations per second (Hertz)
Wavelength = Distance from the peak of a wave to the next peak. (m)
HW Plan and Observation section of coursework in for next Thurs.
RM 09/09/04 5B
As above. AP has lines, AE will get some lines.
RM 13/09/04 5B
We looked at wave effects in sound. Particularly drawing attention to the fact that a sound wave is longitudunal, but can be represented on a graph which looks like a transverse wave. Amplitude and wavelength are shown on a displacement vs. distance graph. (Like a picture of a wave at a certain time.) Amplitude and period are shown on a Displacement vs. Time graph (what happens to one part of the wave over time.)
Coursework to be returned will come to forms (tomorrow morning in registers I hope). Light as a wave next.
AP owes me lines, AE also.
RM 16/09/04 5C
Only seven people in. We did some practise questions on waves and sound. We talked about light as a wave for a small while. Coursework was taken in. All people will be given their current P and O marks on Monday.
HW Analysis is due in next Thursday.
OM and RC will see me at Monday lunchtime.
RM 16/09/04 5B
We observed laser light diffracting through a single slit, and then several slits. The slits were very thin, remember that the width of the gap must be similar to the wavelength of the wave if diffraction is to occur. The wavelength of our light was 0.6 millionths of a meter. The slits were wider than this, but still really quite small. When several slits were put in the way of the laser, the diffraction pattterns from each slit overlapped and interfered with each other. This lead to a series of light and dark patches on the screen where there was constructive and destructive interference respectively.
HW: Analysis section of coursework is due in next Thursday.
RM 20/09/04 5B
We ditched plans to learn of refraction and just went through some coursework theory in order that everyone can happily get P6. For O, it is necessary for you to show your raw data (not averages or converted into Newtons values) in your table. Also, keep to the same number of significant figures throughout, don't make your readings appear more or less accurate than they were.
HW Analysis on Thursday please, along with any updates to P and O.
RM 20/09/04 5C
We also ditched refraction plans. Instead, a brief summary of the main points needed for good coursework marks. Follow the mark scheme, remember, fair test, science (energy changes and losses) and a prection for P6a. A very good version of P6a gets P8a really. P8b is preliminary work written out well. Results table must be all at the same level of significant figures. Raw data must be included.Analysis is your graph plus comments on your graph. Processed data is needed for A6a.
HW Analysis on Thursday please, along with any updates to P and O.
RM 23/09/04 5C
We looked at optical fibres. They make use of Total Internal Reflection (TIR) to send light down tranparent "pipes" made of plastic or glass. Information can be sent down these pipes by varying the intensity of the light. In general, light is sent down as a series of coded on and off pulses (e.g. binary code. Digital signals work better over long distances as their information is much harder to change if the signal degrades slightly. Optical fibres are better than electrical cables as they are much lighter and smaller, and can carry vastly more information. Signals do not fade away so quickly, so many fewer repeater stations are required. They also do not suffer from interference and cannot be tapped unlike electrical cables.
Microwaves are electromagnetic waves, like light. This means that they can travel through a vacuum and go at the speed of light (300 million m/s). However, they are not visible as they have a much larger wavelength and a much smaller frequency than visible light. However, they were shown to exhibit all the wave behaviour that we have seen before. Diffraction and interference, and reflection just as in all the waves we have seen.
HW Evaluation of coursework is due in next Thursday.
RM 23/09/04 5B
As 5C
RM 27/09/04 5B
The electromagnetic spectrum: light is just one range of frequencies of the whole spectrum of electromagnetic waves. They are unique in that they can travel through a vacuum without the need for any kind of matter to be there as a medium. They are comprised of an oscillating electric and magnetic fields.
You need to know the various properties of each type of electromagnetic waves, what they are used for, and the dangers they pose to humans.
Spectrum goes as follows:
Radio waves, microwaves, infra red, light, ultraviolet, X-rays, gamma rays
(in order of increasing wavelength)
HW: Coursework Evaluation needs doing for Thursday. It is only worth 6 marks and must be a comment on the accuracy and effectiveness of your experiment rather than anything about the science of what went on.
RM 27/09/04 5C
As 5B
RM 30/09/04 5C
We watched some vids on the electromagnetic spectrum. The shorter the wavelength, the more energy a wave carries and the more damaging it can be to humans. You need to know the uses of the various waves and the dangers.
We did a bunch of past paper questions on waves, we just have Seismic waves and tectonic plates to go and then a test.
HW Final draft of coursework is due in next Thursday. After that, coursework will not be discussed during lesson time, you may submit improvements if you are unhappy with your mark.
RM 30/09/04 5B
As 5C
RM 04/10/04 5B
We watched a seismic waves vid. There are 2 types of waves produced when an earthquake happens. P waves are longitudunal and S waves are transverse. Only P waves can travel through liquid parts of the interior of the Earth. P waves are faster than S waves but S waves tend to cause most damage to builings as they cause lateral shaking of the ground. More on this next time.
HW All coursework finished for Thursday. Anyone without a mark for each section after then will be liable for punishment.
RM 04/10/04 5C
As 5B
RM 07/10/04 5C
We finished off seismic waves. The outer part of the Earth (the crust and the upper, solid part of the mantle (the lithosphere) are divided up into seperate plates which all float on the liquid rock below. They are pushed around by convection currents in the molten rock and so moved around. Where they are moving towards each other, the crust gets "crumpled" and mountain ranges are formed. Where they are moving apart, lava comes up to fill the gap between plates and new crust is formed. Volcanoes tend to form in these regions. When plates are rubbing past each other, huge amounts of tension are built up until it is suddenly released and an Earthquake occurs. This produces P and S waves as in the previous lesson.
HW There will be a test on waves on Monday. Revise for it. Absentees will have checked the website and therefore know all about it. If not, tough, check the website next time. Go to an internet cafe if you have to. It's not that hard.
RM 07/10/04 5B
Very much as 5C.
EG and EF-W will see me at breaktime or gain a detention.
RM 11/10/04 5B
We sat the waves test. DTs await for thosae who don't have complete coursework.
RM 11/10/04 5C
As 5B.
RM 14/10/04 5C
Conduction, convection and radiation were demonstrated. They are the 3 ways of getting heat energy from one place to another.
HW AQA book page 159-161 Qs 1-7.
RM 14/10/04 5B
Demonstrations cut short, lots of work for you little lot. Conduction, convection and radiation were defined as the 3 methods of getting heat energy from one place to another.
HW Physics Matters P123 "Convection" all questions and make sure sheet 5.4 is completed it will also be marked for on Monday.
RM 18/10/04 5B
We went through the seismic wave test. Then some notes on cavity walls (prevent conduction) and sea breezes (convection currents).
HW Answer PM "Conduction" chapter questions. (2 pages before last HW.) on paper for Thurs.
RM 18/10/04 5C
More work on heat transfer. Cavity walls (prevent conduction) and sea breezes (convection currents) were covered as well as Thermos flasks. They avoid all 3 methods of heat transfer which is why they are so good at keeping your coffee warm.
HW Sheet of GCSE questions on heat transfer.
RM 21/10/04 5C
We saw some fantastic '60s videos on conduction, convection and radiation. We then answered PM questions on the same.
HW Do "radiation" questions from PM P124-125 and revise for a test on conduction, convection and radiation.
RM 21/10/04 5B
We saw 2 of the same old videos as 5C, and once more trawled through the ideas of conduction, convection and radiation. Paint things matt black if: a) they are for some reason hotter than their surroundings and you would like them to cool down (matt black is an excellent emitter of heat radiation)
or b)They are cooler than their surroundings and they are illuminated with infra red radiation and you would like them to warm up.
Paint things white if they are hotter than their surroundings and you would like them to stay that way, or they are colder than their surroundings and you would like this to remain so. (white is a poor absorber and emitter of infra red radiation.)
HW GCSE questions and revise for a test on conduction, convection and radiation.
RM 01/11/04 5B
We sat the little test on conduction, convection and radiation. People who went to Berlin got a copy of the HW Qs, to get done over the next week or so. Physics Matters questions on convection and conduction must be handed in by everyone. Check out revision quizzes on the main page - could well be handy.
RM 01/11/04 5C
Little test on conduction, convection and radiation. Heat transfer practise Qs must be completed by everyone for next time.
RM 04/11/04 5C
We went throught the test on convection conduction and radiation. Mostly done OK except for EC, JF and JD. They require some extra stuff on this during a lunchtime next week. We started to look at optical devices. Lenses use the refractive properties of glass/plastic to bend light in useful ways. Convex lenses bend parallel rays of light inwards, concave lenses bend them outwards.
Convex lenses are used in cameras to form a small, upside down image of a far away object. (large object creates small image on photographic film.) They are used in slide projectors to form a large, upsidedown image of a small, fairly nearby object. (e.g. small slide close to lens creates large picture on screen.) They can also form a large, virtual image which is the right way up if the lens is held very close to the object. (i.e. like a magnifying glass). They are used in the correction of long sight.
Concave lenses are used in the correction of short sight.
HW AQA book Pages 121-122 all questions.
RM 04/11/04 5B
We started to look at optical devices. Lenses use the refractive properties of glass/plastic to bend light in useful ways. Convex lenses bend parallel rays of light inwards, concave lenses bend them outwards.
Convex lenses are used in cameras to form a small, upside down image of a far away object. (large object creates small image on photographic film.) They are used in slide projectors to form a large, upsidedown image of a small, fairly nearby object. (e.g. small slide close to lens creates large picture on screen.) They can also form a large, virtual image which is the right way up if the lens is held very close to the object. (i.e. like a magnifying glass). They are used in the correction of long sight.
Concave lenses are used in the correction of short sight.
HW AQA book Pages 121-122 all questions.
RM 08/11/04 5B
More on optical devices. We saw an optical bench with a convex lens acting like a camera and a slide projector. The image is inverted side to side aswell as vertically.
HW Sheet of questions on lenses.
RM 08/11/04 5C
As 5B really. AQA P121-122 must be handed in for Thursday or all sorts of trouble.
HW Sheet of questions on lenses
RM 11/11/04 5C
We finished off optics. For all ray diagrams involving lenses:
HW Finish the past paper under close to test conditions please so I can figure out what needs to be concentrated on for revision.
HW Also, anyone with 2 missing HWs gets a Detention next Thursday. I am totally serious about this, check the website if you don't know what you haven't done.
RM 11/11/04 5B
As 5C. HW gaps must be sorted out by the end of next week.
RM 15/11/04 5B
We started to revise simple electricity. Tests will be marked to see what other topics most need time spent on them. Homework gap people must have this problem sorted by the end of the week (CCF camp on Thurs so it will just be cover work on electricity.)
RM 15/11/04 5C
Revision of simple electricity. Tests will be marked to see what needs most work. People who haven't handed their tests in by tomorrow morning are in big trouble. If you want to collect a detention then this is a good way to go about it.....
RM 18/11/04 5C
We went through V=IR, P=IV and Energy = Power * time and household electricity.
RM 18/11/04 5B
RM absent. Practise questions done on all simple electricity for those who were present.
RM 12/11/04 5B
Revision of simple electricity continued - we move on next time.
RM 22/11/04 5C + 5B
Practise of simple electricity doing some questions. We move onto electrostatics and electromagnetism next time.
RM 25/11/04 5C + 5B
Electrostatics was revised. Electrons are negatively charged and orbit the positive nucleus of atoms. You can charge an insulator by rubbing it against another suitable insulator. Electrons are rubbed from one surface onto another leaving an overall negative charge on one object and an overall positive charge on the other.
Alike charged objects repel each other, and unlike charges attract. Charged objects can attract small neutral objects by inducing a temporary dipole in them.
Gold leaf electroscopes show when they are charged by the gold leaf standing out. The gold leaf and the metal plate have the same charge and so repel each other.
Static electricity is used in photocopying. A positive charged imprint of the writing you want to copy is created on a plate. (Light reflects off the document you want to copy and causes the charge on the plate to leak away, except the black bits where the charge stays.) The toner (ink) is then given a negative charge and fired at the plate. It only sticks to the charged bits, and the plate then stamps the image onto the blank paper to make a permanent copy.
Other uses you must be aware of are in removing soot particles from smoke and in spraying cars.
HW P59 Q1 (electrostatics) and P62 Q10 (potential dividers)
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u>RM 29/11/04 5B + 5C We went over control in circuits (potential dividers). The battery voltage is always shared between the components in a series circuit. The components with the most resistance get the larger share of the voltage.
Vcomponent = Vbattery * Rcomponent/Rtotal
If a sensor component (LDR or thermistor) is put into one of these circuits, it changes in resistance depending on an outside variable. The voltage across each component therefore changes.
A transistor is a switch which turns on when there is a high enough voltage present at its input leg. The transistor can therefore be used with one of the above circuits to turn on an output device suddenly when a specified temperature or light level has been reached.
The voltage across a capacitor varies over time as it charges up. A capacitor can be used to introduced time delay into a potential divider circuit.
More on capacitors, next time, a tiny bit on logic gates (you are good at them already) and then onto radioactivity (which needs some work.)
RM 02/12/04 5C We finished of ideas about control in circuits. Then radioactivity was looked at, revision materials handed out.
We also had a recap of the transimission of electricity. A transformer is used to step up the voltage of electricity generated at the power station. This is done by having more turns in the secondary coil of the transformer than in the primary coil. The voltage is greatly increased, but the current is greatly reduced to send the electricity through the overhead pilons. (Power = Current * Voltage, so stays the same). A low current means that much less energy is lost as heat in the wires (fewer electron collisions). A second transformer must be used to step the voltage down for safe use in ther home.
Alternating current (a.c.) is required for transformers to work (the 2nd coil picks up a voltage due to the changing magnetic field of the first coil.)
HW - Do the last page only of the GCSE radioactivity question sheet.
RM 02/12/04 5B We briefly talked about capacitors for control in circuits. The voltage across a capacitor builds up slowly when it is connected into a circuit. They can therefore be used to introduce a time delay into a potential divider circuit using a transistor.
Radioactivity was poorly done in the GCSE paper. Therefore revision material was handed out and we went through the main issues involved. We then did some practise questions. We shall move onto moments and centres of mass next week - the last topic to be covered before X-mas.
HW Complete the GCSE questions sheet for Monday.
RM 06/12/04
A brief and easy question on capacitors, just to show you how easy they really are.
Then we talked about moments. The moment of a force is the turning effect of that force about a certain point.
Moment = Force * Distance from pivot
When something is in equilibrium (balanced), the moments clockwise and anti clockwise must be the same. The inevitable see saw calculations were attempted.
A bit more on this and centre of mass next time.
HW Qs 1-6 P85 will be marked in your books. Radioactivity sheets were due in today, get them in asap if they didn't arrive today.
Coursework - All your work must contain at least one hand drawn graph. Processed data is needed for better than A5/6 (means drawing a graph with processed data in).
RM 08/12/04 5C + 5B
Moments and centres of mass were completed as a topic. All pretty simple stuff. Stable objects have a wide base and low centre of gravity, unstable objects the opposite.
HW Finish coloured GCSE questions.
Coursework must be handed in before Xmas.
RM 13/12/04 5C + 5B
Forces and motion and waves syllabus sections recieved. NEAB paper 1998 embarked upon. Most questions here are relevant. Post mock topics are: Circular motion, momentum and the Earth in space. Ignore these.
HW Hand in a copy of your coursework to me whether it is in it's final state or not.
RM 16/12/04 5C
JB is a hero. Work energy and power were briefly pondered upon, and generators and transformers.
Hard copies of coursework to me before the end of the week.