AS PHY PRACTICAL 33

[Ariel Robert]

I guess I'll just study every paper 3 tonight before the exam. No idea on my apparatus.

Paper 31 its all gonna be Mechanical

there will definitely be a torque question, related to finding mass of rule.

The second one im looking for... Hope it helps..

 

[SYED ALI ARIZ]

what wil be the shape of the graph in q1 (electricity)????
ANY GUESSES STRAIGHT LINE OR CURVE???

 

[MustafaMotani]

what wil be the shape of the graph in q1 (electricity)????
ANY GUESSES STRAIGHT LINE OR CURVE???

it has always been a straight line ... as far as we have done practicals in lab

 

[Muhammad Nashit]

then w

yeah that's probably variable resistor


I'm also unsure about absolute uncertainty, isn't it supposed to be least count/2?

whats the use of a rheostat?? -_-

 

[MustafaMotani]

then w
whats the use of a rheostat?? -_-

we dont have to use all the things provided ... so i guess that cardboard wire is useless

 

[abdullahaftab]

Guys Plz reply Quick. How to find percentage Uncertainty??

For example If I measure an objects diameter I get three reading 5.67cm 5.68com 5.66cm the diameter would be (5.67+5.68+5.66)/3 and as 1 reading has a uncertainty of 0.1cm the final average reading will have the uncertainty 0.3. Is this Method Right

 

[aleezay]

Can you please explain further what you mean, I don't quite get it. 'Calculated value is a measurement', I guess you mean that if two values are taken and added or subtracted then we add the uncertainties together (and since taken from same instrument it's same was x2)

Yes, but apart from that, your 'reading' is actually a measurement in the sense that 0 has error +-.005 and any mark,say 20.0, has the same error. So reading in 20.0 is +-.01.. I hope this cleared your confusion

 

[skylexgale]

then w
whats the use of a rheostat?? -_-

sorry I meant to say independent resistor, not variable

 

[aleezay]

im hearing ke time from stop watch has to be given to 2 dp ? please confirm

Yeap.

 

[skylexgale]

Yes, but apart from that, your 'reading' is actually a measurement in the sense that 0 has error +-.005 and any mark,say 20.0, has the same error. So reading in 20.0 is +-.01.. I hope this cleared your confusion

So do we always do it like that?

Like for example I am asked to measure a length of wire, I get answer 20.0 cm

lets say least count on my meter rule is 0.1 cm

then they ask me for absolute uncertainty

I will say (0.05 + 0.05)/2 ? or will I say 0.05/2?

 

[aleezay]

we dont have to use all the things provided ... so i guess that cardboard wire is useless

What if we have to measure its diameter?

 

[aleezay]

So do we always do it like that?

Like for example I am asked to measure a length of wire, I get answer 20.0 cm

lets say least count on my meter rule is 0.1 cm

then they ask me for absolute uncertainty

I will say (0.05 + 0.05)/2 ? or will I say 0.05/2?

.1/20.0.. Ive gone through like 45 marking schemes.. Never found .05mm as the uncertainty..

 

[selena]

how to arrange the circuit as in oct/nov 2012 p34 pls reply fast specially the rheostat

 

[skylexgale]

.1/20.0.. Ive gone through like 45 marking schemes.. Never found .05mm as the uncertainty..

okie thanks

A few more things

1. If say I was asked to add two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

2. If say I was asked to subtract two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

3. If say I was asked to multiply two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

4. If say I was asked to divide two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

 

[aleezay]

So do we always do it like that?

Like for example I am asked to measure a length of wire, I get answer 20.0 cm

lets say least count on my meter rule is 0.1 cm

then they ask me for absolute uncertainty

I will say (0.05 + 0.05)/2 ? or will I say 0.05/2?

For example w08.p31.Q2(a)(ii) we were to use a metre rule to determine d.. theyve allowed errors of 1 or 2mm for single determination of d but not .5mm

 

[aleezay]

For the first two, yes, except youll write L1-L2 in the denominator for case 2. For the other 2, error is {0.1/L1+ 0.1/L2} multiplied by their product or quotient

okie thanks

A few more things

1. If say I was asked to add two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

2. If say I was asked to subtract two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

3. If say I was asked to multiply two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

4. If say I was asked to divide two lengths L1 and L1
will uncertainty by (0.1 + 0.1)/(L1+L1)

Hope this helps

 

[selena]

how do you connect wires in variable resistor??

 

[skylexgale]

how to arrange the circuit as in oct/nov 2012 p34 pls reply fast specially the rheostat

turn on hotspotshield or something and watch

 

[HunzaZ]

isnt it

what we were told in the school .... ..

get two values of k ...
then (larger-smaller)/larger x 100

if the value is less than 10% than relationship valid...if greater than 10% then relationship not valid

Isnt it difference in values of k/average value of k X 100 ?

 

[kalpaveen]

can someone please tell me the uncertainity of,
vernier calliper
micrometer
meter rule
stopwatch

also can someone please explain how to prove a relationship??