Physics p33 errors

[rethna30]

hey rethna du have any tips for q1...as u say it might be concerning electricity...

Dude...I saw the past year questions and the electricity related questions usually come first. So, i think that the diode question may be the long question as said by MAVtKnmj( pwewh....hard to spell)....

And oil viscosity may be the second...anyway, we have to be ready for any situations which may be different.

Anybody here have other hints or clues about the diode experiment? Any known materials.....

 

[maximum_user]

any idea hw the diode question would be set...any clues so i can post the revelant material!!!

 

[maximum_user]

http://www.practicalphysics.org/go/Expe ... tion_id=23

 

[maximum_user]

http://www.practicalphysics.org/go/Experiment_235.html

VERY HELPFUL ...

 

[deelo]

I've googled for many sample experiments for this "oil viscocity". And visited a lot of pages to see how the experiment can be done, what are the possible errors, and improvement methods..

These are some of the good answers that I found.

Oil Viscosity

Error

1. small air bubbles are formed on the marble/spheres/(any balls being used) which hindered the motion of the ball
2. two sets of reading not enough to draw a valid conclusion
3. human error in timing
4. marble may have not reached terminal velocity


Method of improvements

1. release the ball/marble just a few mm above the oil surface
2. take more readings and plot a graph
3. use light gate to trigger stopwatch/high speed camera with known time intervals/use video camera with slow motion replay
4. ensure the terminal velocity by increasing the release height/using long tube/measure velocity at two intervals to check terminal velocity reached.

I took three of the errors and method of improvement from october/november 2007 paper 32 question 2 marking scheme.
It is also about terminal velocity.

There are other general improvements that I've found in net...But, I dunno how to state a possible error for them.

1. marble released gently into the top of the solution and that it doesn't touch the side of the tube. Using a wider tube
2. Allow oil to stand for a while to let it settle removing all air bubbles

Another source..
http://www.iop.org/activity/education/P ... e_3683.doc

thanks alot rethna!! it was really of great help..

 

[deelo]

Ppl VISCOSITY is not in our syllabus..!!!! the expt will be about terminal velocity not viscosity!!

 

[vikid-e-vik]

ya ur right.....viscosity...is not in our syllabus....so i guess we should do everything pertaining to terminal velocity....and im guessing there also shud be no questions about viscosity of oil or any other liquid...

 

[bilal_92]

guys guys....plzzzzzz tell me about p34!!!! glass prism thingy nd da magnet!!!plzzzz help needed!!

 

[rethna30]

Ppl VISCOSITY is not in our syllabus..!!!! the expt will be about terminal velocity not viscosity!!

Yeah...i'm thinking the same too...but both experiment are using the same methods, materials and apparatus.

Just that we calculate viscosity using the formula below. But, it's fluid mechanics which is beyond our syllabus....But, sometimes CIE can go crazy... ...


Viscosity = 2(ΔP)ga2
9v

where:

* Viscosity is in newton-seconds per meter squared (Nsec/m2).
* Delta (Δ) P is the difference in density between the sphere and the liquid, and is in kilograms per meter cubed (kg/m3).
* g is the acceleration due to gravity and equals 9.81 meters per second squared (m/s2).
* a is the radius of the sphere in meters (m).
* v is the average velocity, defined as the distance the sphere falls, divided by the time it takes to fall in meters per second (m/s).
Got it from http://www.sciencebuddies.org/science-f ... p055.shtml


The cooooool thing is that errors and improvements that I've mentioned can be used for both experiments,....

 

[vikid-e-vik]

hey i did check the syllabus....and again there is no viscosity.....and i bet its only terminal velocity....and cie cant ask whats not in our syllabus....and plus we hav never done viscosity practicles before....

 

[deelo]

WOW!! u hv got some crazy info..!! nicee..
and the electricity question will be the longer one .i.e. Q1 because we usually hv to draw a graph in it.. wot do u think??

 

[MAVtKnmJ]

The electricity question will be the big question. You will have to setup a circuit with a power supply, ammeter, voltmeter, semi-conductor diode, LED/Resistor and dip the diode in cold water or ice cubes. You will need to measure the temperature with a thermometer before starting to take readings. You will need to vary the voltage and take 5 or 6 readings from the ammeter and voltmeter, draw a table and plot a graph etc.

For the second question, it will be regarding the terminal velocity of two beads when they are dropped in a cylinder filled with oil. You will need to measure the diameters of the beads with a Micrometer Screw Gauge, so do learn how to use it. Next you will need to drop the beads one by one and note the time it took for the beads to travel a certain distance. You will need to measure this distance with a meter rule. Then error and improvements etc.

That's it, hope this helps!

 

[deelo]

are u sure about this ??

 

[cool]

i don't know how to use a micrometer..plz any can explain me..i know how to read the main scale but tell me is it in centimeters or mm? wat about the reading on circular scale..do we have to multiply it by the least count or sumthing?? im also confused between cm and mm??plz reply wid explanation..my chem prac is already screwed.

 

[rethna30]

Hey guys...found this Cambdrige teaching AS Practical Physics in net...

So, download it and have a look at those experiments....they're looking quite similar to those which came out for the previous papers....

Read about terminal velocity there.....

http://www.scribd.com/doc/19920765/Camb ... al-Physics

 

[deelo]

A digital screw gauge will be provided!! no need to panic..

 

[Lemon]

No harm in learning how to use screw Gauge, in any case the cie decides not to provide digital screw gauge. Here http://www.complore.com/using-vernier-calipers-and-micrometer-screw-gauge-0 this site explains it beautifully.

 

[rethna30]

The electricity question will be the big question. You will have to setup a circuit with a power supply, ammeter, voltmeter, semi-conductor diode, LED/Resistor and dip the diode in cold water or ice cubes. You will need to measure the temperature with a thermometer before starting to take readings. You will need to vary the voltage and take 5 or 6 readings from the ammeter and voltmeter, draw a table and plot a graph etc.

For the second question, it will be regarding the terminal velocity of two beads when they are dropped in a cylinder filled with oil. You will need to measure the diameters of the beads with a Micrometer Screw Gauge, so do learn how to use it. Next you will need to drop the beads one by one and note the time it took for the beads to travel a certain distance. You will need to measure this distance with a meter rule. Then error and improvements etc.

That's it, hope this helps!

Yes, you are right....

 

[vikid-e-vik]

wow...thanks a lot....crazy info.....i bet u hav ur sources..MAVtKnmJ....by the way....would anyone reccomend any papers which hav the same type of questions....

 

[rethna30]

Finally, the mystery behind the Physics Paper 33 has been revealed!!!!