How was physics p52

[leosco1995]

would NC^-1 be penalised? in the marking schemes I saw many units.

I think it'll be accepted.

 

[Jobiii]

How were the absolute uncertaintities calculated? 2*(dt/t)*t^2 right?

 

[meobunny]

Sorrryy for such a messed up drawing. But my diagram was something like this :/ is it ok?

 

[Aries_95]

Sorrryy for such a messed up drawing. But my diagram was something like this :/ is it ok?

mine was something of this sort as well!

 

[Jinkglex]

guys is it wrong if we use signal generator to change frequency?
and i connected CRO with coil...is that ok? and CRO needs a seperate power supply right?

my points were basically:

read frequency off time base of CRO
calibrate CRO and check y-gain and time-base before connecting
use large values of F to get large I0
make graph of V0/I0 against f, gradient is 2[pie]2[L]2 from where we will get value of L
Y-intercept will be R2
avoid heated coils by wearing rubber gloves

I cant remember the rest but do those look ok?

 

[no.mercy]

Nice idea you got there, basically the same but you don't use alternator, you move the coil itself so that emf can be induced in that.

And I am pretty sure that frequency was the independent variable and current was the dependent variable.

 

[Basanta]

Here's what i drew.

yes this is exactly what i did

 

[Basanta]

should we consider uncertainty in b while calculating error in E.. or we just calculate using best fit slope and worst fit slope and subtract them???

 

[Silent Hunter]

I think we should have considered the 'b' uncertainty ..... not sure though

 

[Geistpanzer]

And I am pretty sure that frequency was the independent variable and current was the dependent variable.

I think you know this but if you increase either the frequency of the coil oscillation or the alternator, both the voltage and current will rise due to the increase of the rate of change of magnetic flux. That's why there's V0 and Io term are stated on the left side of the equation.

 

[danyaljamil]

could a C.R.O be used to measure the peak alternating current connected in series or is it only for voltage

 

[daniyal007]

I kept the no. of turns in the coil and the current from the power supply constant and used a variable frequency generator to vary the frequency.

I also did the same as u did. I kept number of turns of coil and current in the circuit constant.
I then measured resistance of coil by ohmmeter and Vo by CRO. and then calculated Io by V=IR. Is this correct??? plzzz reply thanx

 

[daniyal007]

signal generat

didnt we have to use type of signal generator ?

signal generaot is also a correct approach of varying frequency of current as written in mark scheme of oct nov 2010 p52

 

[Silent Hunter]

signal generat

signal generaot is also a correct approach of varying frequency of current as written in mark scheme of oct nov 2010 p52

so it wont be considered wrong?

 

[studen12345]

hey i got my uncertanities in the table wrong and it affected my whole question the graph the worst acceptacle and further question is their any ecf how many marks i will loose?iam so sad

 

[saifookhan]

I also did the same as u did. I kept number of turns of coil and current in the circuit constant.
I then measured resistance of coil by ohmmeter and Vo by CRO. and then calculated Io by V=IR. Is this correct??? plzzz reply thanx

Congratulations. You're right.

 

[daniyal007]

so it wont be considered wrong?

exactly !

 

[daniyal007]

Congratulations. You're right.

Em still confusef that either Vo was to be copnstant or current???
secondly, how u cud say with surety that i am right....my most of the friends kept Vo constant....so em really cnfused atlarge!

 

[Geistpanzer]

Em still confusef that either Vo was to be copnstant or current???
secondly, how u cud say with surety that i am right....my most of the friends kept Vo constant....so em really cnfused atlarge!

They're both variable, that's why they're on the left side of the equation. If you increases the frequency of the generator, the emf will also increase and thus the current as well. That said, you can keep one of them constant by complicated mechanism which I think is not too appropriate for a level purpose.

 

[blabla]

Okay guys, here what i did for the design question.

I used a frequency oscillator to oscillate the coil, put two electromagnets on the sides. Emf induced or current induced was recorded on the CRO. Frequency was varied and the current was recorded.

omg thank god someone did something similar to what i did! instead of moving the coil, i moved an electromagnet through the coil though. But i had the same idea - in this way i varied the frequency by varying the speed at which i moved the magnet (v=2πfr, where i kept r of coil constant so varying v meant varying f) and attached a cro to measure corresponding peak current. hope it makes sense