Uncertainties(i think it's spelled like that)

[Scafalon40]

I read this:
Relates to physics P3
Estimation of uncertainty and percentage uncertainty.

In some papers you will be asked to calculate a simple percentage uncertainty or state the uncertainty in a measurement. When repeated readings have been done then it is expected that the uncertainty will be half the range. Use the expression:

Percentage uncertainty = uncertainty/average value x 100

If single readings have been taken then the uncertainty should be half of the smallest interval on the measuring instrument (assuming no zero error).
What does ' it is expected that the uncertainty will be half the range' mean?

 

[CaptainDanger]

Yeah you spelled it correctly!

For example you take two readings of diameter of a wire... .22mm and .23mm... So uncertainty can be half of these values range... Subtract them and divide it by two
(.23 - .22)/2 = .01/2 = +- .005 is the uncertainty in this case... It can be more than two values... You have to find the range of the values and then divide it by two...

 

[Scafalon40]

Yeah you spelled it correctly!

For example you take two readings of diameter of a wire... .22mm and .23mm... So uncertainty can be half of these values range... Subtract them and divide it by two
(.23 - .22)/2 = .01/2 = +- .005 is the uncertainty in this case... It can be more than two values... You have to find the range of the values and then divide it by two...

I see...
You must've noticed this statement of 'range' over and over again in the marking schemes, but it always goes like this "if repeated readings have been taken then uncertainty can be half the range"
does that mean that I do not have to use this method i.e I can just use the absolute uncertainty method, even when I have taken repeats
Thanks for you post, though

 

[CaptainDanger]

Exactly! Any will work...

 

[Scafalon40]

Thanks

 

[CaptainDanger]

 

[fatimanaeem]

Plz help me with use of s.f in all papers!

 

[thunderingthunder]

Plz help me with use of s.f in all papers!

what kind of help do you need with the significant figures?=/

 

[fatimanaeem]

Actually relating sig.fig. u use in ur answer to the data given in the question...its giving me a tough time..