Physics P3 (Practical) Notes and Tips

[Suchal Riaz]

How many significant figures do we give for percentage uncertainity?

same as least number of sig fig used in calculations

 

[saqib.tariq]

same as least number of sig fig used in calculations

can u explain question 2 basic ideaa http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w07_qp_31.pdf

 

[Jassim]

Alright guys. Get your sleep. Nothing worse than waking up unalert. I ain't bossing you around or any of that shizz, but you need a really focused mind for practicals. Just make sure to read the theory again, all uncertainties in instruments, logs/linear law in case it comes, remember that all values in a column must have the same number of sig figs, all time values (analogue or digital) read to 0.1s, fake the averages if you're confident and revise the limitations and errors again, which I'm pasting an updated copy for below. Don't panic too much, even if you think you're messing it up. Of course, pray to Allah for good grades and be grateful for the access to teachers and whatever resources you had.
-----------------------------------------------------------------------------------------------------------------------------------------------
I compiled a new list of errors and improvements for the last part of question 2 in physics paper 3. Only the first one you can use everywhere, as long as the question requires taking any type of measurement at all. These are all from the past papers marking schemes. These could be helpful if you're running out of time and had memorized these before, but please make sure these error and improvements fit the question!

1. Error: Two readings not enough to support the conclusion
Improvement: Take more sets of readings and plot a graph/compare values of k
(This one works everywhere. Memorize this!)

2. Error: Large uncertainty in measured quantity because quantity is too small (like when measuring the thickness of an object)
Improvement: improved method to calculate this quantity like taking more readings at different parts of the object and dividing by number of readings for an average.

3. Error: Friction with surface (apply to any object that you have to pull on a surface)
Improvement: apply lubricant to surface

4. Error: (only when newton meter used horizontally!) Zero error on newton meter when used horizontally.
Improvement: adjust vertical arrangement of newton meter.

5. Error: (Keeping an object at certain height with your hands for a long time) keeping "object" at a certain height difficult
Improvement: use a clamp/tape.
ELECTRICITY:

6. Error: Voltmeter scale not sensitive enough/not precise enough
Improvement: Use a digital voltmeter/use a voltmeter that reads to 0.01 V.

7. Error: Wire not straight/wire kinked (coils) / difficulty in keeping wire straight
Improvement: Tape wire to a ruler/ clamp wire.

8. Error: Contact resistance/fluctuating ammeter or voltmeter readings
Improvement: Sand the crocodile clips to clean them/ tighten clips

OSCILLATIONS

9. Error: Difficult to judge start/center/ end of swing / complete swing
Improvement: use fiducial marks/pointer

10. Error: large uncertainty in time / time taken too short
Improvement: use video and timer that captures frame by frame video

15. Error: Difficult to mark rebound height/final position
Improvement: Use a high speed camera that has slow motion playback and use a data logger.
-------------------------------------------------------------------------------------------------------------
11. Error: Object does not travel in a straight line
Improvement: Method of guiding object to travel in a straight line/narrow tube (if ball moving inside)

12: Error: (when measuring degrees in an experiment that's suspended in the air like the degrees between a rubber band when stretched) difficult to hold protractor steady
Improvement: project image of the rubber band onto a screen.

13: Error: applying a force on the object when releasing it/impossible to release object without applying a force.
Improvement: use an electromagnet release clamp to release the object so it falls/moves on a slope or surface under the force of its own weight.

14. Error: Air currents may cause variation in path of object (KEEP IN MIND THE MASS OF THE OBJECT AND BE REASONABLE)
Improvement: Close fans and air conditioners, shield object from draughts.

16. Error: Difficult to make accurate cylinder shape
Improvement: Use a cylinder mold to make and accurate shape/method of making accurate cylinder.

17. Error: inconsistent ball bounce/ball bounces (on surface) at an angle.
Improvement: use a smoother brick.

18. Error: Friction at pulley
Improvement: Lubricate pulley

19. Error: Retort stand moves
improvement: Clamp stand to bench/table

20. Error: Labelled value of mass may not be accurate
Improvement: use a top pan balance to find mass.

21. Error: Large uncertainty error in thickness
Improvement: Measure more layers of paper/(object) OR use micrometer screw gauge for better precision.

-------------------------------------------------------------------------------------------------------------

Meter Rule: 0.1 cm = 1mm = 0.001m
Vernier Caliper: 0.01cm = 0.1mm
Micrometer: 0.001cm = 0.01mm
Protractor: 0.1 or 0.2 degrees (depending on experiment)
Time: 0.1s

Important: Also google pictures of DIGITAL MULTIMETERS and learn how to use them. Good night people. Remember me in your prayers

 

[Jassim]

what to do with potentio meter? tell me about it i haven't revised anything with it please

Open up may june 2013 P33. Read through the question and the marking scheme. Then open up Oct 2010 P33. Google how to connect a rheostat to a circuit (one clip goes to top knob on one side and the other to the bottom knob). And google how to use Digital Multimeters. Its very important. Also read up on my oscillation errors. I'm sorry I can't explain in greater detail but I have little time left for the night.

 

[Suchal Riaz]

Alright guys. Get your sleep. Nothing worse than waking up unalert. I ain't bossing you around or any of that shizz, but you need a really focused mind for practicals. Just make sure to read the theory again, all uncertainties in instruments, logs/linear law in case it comes, remember that all values in a column must have the same number of sig figs, all time values (analogue or digital) read to 0.1s, fake the averages if you're confident and revise the limitations and errors again, which I'm pasting an updated copy for below. Don't panic too much, even if you think you're messing it up. Of course, pray to Allah for good grades and be grateful for the access to teachers and whatever resources you had.
-----------------------------------------------------------------------------------------------------------------------------------------------
I compiled a new list of errors and improvements for the last part of question 2 in physics paper 3. Only the first one you can use everywhere, as long as the question requires taking any type of measurement at all. These are all from the past papers marking schemes. These could be helpful if you're running out of time and had memorized these before, but please make sure these error and improvements fit the question!

1. Error: Two readings not enough to support the conclusion
Improvement: Take more sets of readings and plot a graph/compare values of k
(This one works everywhere. Memorize this!)

2. Error: Large uncertainty in measured quantity because quantity is too small (like when measuring the thickness of an object)
Improvement: improved method to calculate this quantity like taking more readings at different parts of the object and dividing by number of readings for an average.

3. Error: Friction with surface (apply to any object that you have to pull on a surface)
Improvement: apply lubricant to surface

4. Error: (only when newton meter used horizontally!) Zero error on newton meter when used horizontally.
Improvement: adjust vertical arrangement of newton meter.

5. Error: (Keeping an object at certain height with your hands for a long time) keeping "object" at a certain height difficult
Improvement: use a clamp/tape.
ELECTRICITY:

6. Error: Voltmeter scale not sensitive enough/not precise enough
Improvement: Use a digital voltmeter/use a voltmeter that reads to 0.01 V.

7. Error: Wire not straight/wire kinked (coils) / difficulty in keeping wire straight
Improvement: Tape wire to a ruler/ clamp wire.

8. Error: Contact resistance/fluctuating ammeter or voltmeter readings
Improvement: Sand the crocodile clips to clean them/ tighten clips

OSCILLATIONS

9. Error: Difficult to judge start/center/ end of swing / complete swing
Improvement: use fiducial marks/pointer

10. Error: large uncertainty in time / time taken too short
Improvement: use video and timer that captures frame by frame video

15. Error: Difficult to mark rebound height/final position
Improvement: Use a high speed camera that has slow motion playback and use a data logger.
-------------------------------------------------------------------------------------------------------------
11. Error: Object does not travel in a straight line
Improvement: Method of guiding object to travel in a straight line/narrow tube (if ball moving inside)

12: Error: (when measuring degrees in an experiment that's suspended in the air like the degrees between a rubber band when stretched) difficult to hold protractor steady
Improvement: project image of the rubber band onto a screen.

13: Error: applying a force on the object when releasing it/impossible to release object without applying a force.
Improvement: use an electromagnet release clamp to release the object so it falls/moves on a slope or surface under the force of its own weight.

14. Error: Air currents may cause variation in path of object (KEEP IN MIND THE MASS OF THE OBJECT AND BE REASONABLE)
Improvement: Close fans and air conditioners, shield object from draughts.

16. Error: Difficult to make accurate cylinder shape
Improvement: Use a cylinder mold to make and accurate shape/method of making accurate cylinder.

17. Error: inconsistent ball bounce/ball bounces (on surface) at an angle.
Improvement: use a smoother brick.

18. Error: Friction at pulley
Improvement: Lubricate pulley

19. Error: Retort stand moves
improvement: Clamp stand to bench/table

20. Error: Labelled value of mass may not be accurate
Improvement: use a top pan balance to find mass.

21. Error: Large uncertainty error in thickness
Improvement: Measure more layers of paper/(object) OR use micrometer screw gauge for better precision.

-------------------------------------------------------------------------------------------------------------

Meter Rule: 0.1 cm = 1mm = 0.001m
Vernier Caliper: 0.01cm = 0.1mm
Micrometer: 0.001cm = 0.01mm
Protractor: 1 degree
Time: 0.1s

Important: Also google pictures of DIGITAL MULTIMETERS and learn how to use them. Good night people. Remember me in your prayers

protactor 0.1 degree or 0.2 degree
but it depends on the experiment. it it's difficult to hold then take several readings and find difference in max and min reading and half it. this is the absolute error.

 

[Suchal Riaz]

can u explain question 2 basic ideaa http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_31.pdf

what basic idea be more specific

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_31.pdf

Q1d please tell me how to find the units for such questions and what makes it different from other questions !

and how to find the percentage uncertainty and what differs in % uncertainty in one instrument from another

 

[100]

To find % uncertainty
If analogue then least count/2 divided by measured value *100
If digital then least count divided by measured value * 100

Different measuring apparatus have different uncertaintys because of difference in least count

The gradient is 1/p unit of gradient is found by diving units of y and x axis
Y intercept has same unit as what's on the y axis so here q will have unit of y axis divided by unit of p
Hope this helped good luck for Tomorrow

 

[Hijab]

Open up may june 2013 P33. Read through the question and the marking scheme. Then open up Oct 2010 P33. Google how to connect a rheostat to a circuit (one clip goes to top knob on one side and the other to the bottom knob). And google how to use Digital Multimeters. Its very important. Also read up on my oscillation errors. I'm sorry I can't explain in greater detail but I have little time left for the night.

i have a question........... digital stop watches give time to two decimal places (atleast the ones we use in our labs) so would i be giving time to two decimal places i.e 0.01 seconds... kindly reply asap... i would really be grateful

 

[Hijab]

same as least number of sig fig used in calculations

i have a question........... digital stop watches give time to two decimal places (atleast the ones we use in our labs) so would i be giving time to two decimal places i.e 0.01 seconds... kindly reply asap... i would really be grateful

 

[Suchal Riaz]

i have a question........... digital stop watches give time to two decimal places (atleast the ones we use in our labs) so would i be giving time to two decimal places i.e 0.01 seconds... kindly reply asap... i would really be grateful

take it upto one d.p because it is impossible for a human being to take time correct to 0.01 second or even 0.05 seconf. 0.1 is best.

 

[..sacrifice4Revenge..]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w07_qp_31.pdf
question 2 all give me some idea plzzzzzzzzz how to do it ??

nah!
do qs1 of it. :3

 

[Autumngirl]

same as least number of sig fig used in calculations

Thank you

 

[Autumngirl]

If I'm unsure about an error and it's improvement and I write extra ,suppose 5 pairs, will the last one be considered if it's written out of the lines? Suppose the extra is right and one in the lines is wrong so will I get the marks for it?

 

[Jassim]

If I'm unsure about an error and it's improvement and I write extra ,suppose 5 pairs, will the last one be considered if it's written out of the lines? Suppose the extra is right and one in the lines is wrong so will I get the marks for it?

Won't be considered. Make sure all error and their improvements are under the same bullet point. (Error 1 has improvement number 1). One way of doing these errors and uncertainity are while doing the experiment, ask yourself why you are having difficulty with some specific thing, and make sure to write that down, also go take a look at my errors and improvements compilation I've posted. It might help you during the paper. Question 2 is all about errors. Even while taking the instrumental error to find the percentage uncertainity, it will very rarely actually be the error of the instrument only. For anything that's being released and it moves, or anything manually held by you, something like a pencil, the error would not be the smallest scale division but something like S.S.D x 3. This is to account for HRTE and other errors. Suchal Riaz correct me if I'm wrong. (I shouldn't be)

 

[hellblender]

is it the same for oscillation timings that time should be to o.1s or should it be 2 d.p?

 

[Wolfgangs]

I know this topic must not be here, but for biology paper 31, were we supposed to use the eyepiece graticule in any of the questions? And for the chains of xylem vessels, they were three circles only, right?

 

[Wolfgangs]

If x/m, then √x will be r √m or just m?

 

[Mohammed salik]

If x/m, then √x will be r √m or just m?

It would Be m^1/2!

 

[Autumngirl]

Won't be considered. Make sure all error and their improvements are under the same bullet point. (Error 1 has improvement number 1). One way of doing these errors and uncertainity are while doing the experiment, ask yourself why you are having difficulty with some specific thing, and make sure to write that down, also go take a look at my errors and improvements compilation I've posted. It might help you during the paper. Question 2 is all about errors. Even while taking the instrumental error to find the percentage uncertainity, it will very rarely actually be the error of the instrument only. For anything that's being released and it moves, or anything manually held by you, something like a pencil, the error would not be the smallest scale division but something like S.S.D x 3. This is to account for HRTE and other errors. Suchal Riaz correct me if I'm wrong. (I shouldn't be)

I've already gone through your list. It's nice and concise, wish it had been there for my Mocks! I'll try and keep my mind open then instead of trying to remember every single error from memory. Thanks for the help!