IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: $!$RatJumper$!$ on October 24, 2010, 02:27:14 pm

Title: AS Phys Prac Errors & Improvements
Post by: $!$RatJumper$!$ on October 24, 2010, 02:27:14 pm
Guys we all know how frustrating those errors and improvements can be on the last page of a physics prac lol
Have you guys got any tips or certain things to remember when writing down these errors and improvements? I've looked at a lot of past paper questions and there seems to be a variety of different things in each practical that you can write, but the thing is, i would have never thought about some of those in an exam. So if you have anything that would help please share!

Thankx :)
Title: Re: AS Phys Prac Errors & Improvements
Post by: elemis on October 24, 2010, 03:05:12 pm
Repeat the experiment ?

When measuring things use a measuring apparatus with a lower uncertainty.
Title: Re: AS Phys Prac Errors & Improvements
Post by: $!$RatJumper$!$ on October 24, 2010, 03:33:30 pm
Repeat the experiment ?

When measuring things use a measuring apparatus with a lower uncertainty.

Thank you for that :) the lower uncertainty is a good point!
any others?
Title: Re: AS Phys Prac Errors & Improvements
Post by: Deadly_king on October 24, 2010, 03:35:20 pm
Guys we all know how frustrating those errors and improvements can be on the last page of a physics prac lol
Have you guys got any tips or certain things to remember when writing down these errors and improvements? I've looked at a lot of past paper questions and there seems to be a variety of different things in each practical that you can write, but the thing is, i would have never thought about some of those in an exam. So if you have anything that would help please share!

Thankx :)

It usually depends on the experiment being carried out. But in most cases these two applies :

Error : Two sets of values are not enough to draw a valid conclusion
Improvement : Repeat experiment and take maximum number of measurements so as to be able to plot a graph. This is a means of averaging.

Error : It is difficult to judge the measurement since it is instantaneous. hence we should be estimating which is not very accurate.
Improvement : Record the experiment with a camera and use slow motion playback to record measurements as accurately as possible.

Hope it helps ;)
Title: Re: AS Phys Prac Errors & Improvements
Post by: $!$RatJumper$!$ on October 24, 2010, 06:54:24 pm
It usually depends on the experiment being carried out. But in most cases these two applies :

Error : Two sets of values are not enough to draw a valid conclusion
Improvement : Repeat experiment and take maximum number of measurements so as to be able to plot a graph. This is a means of averaging.

Error : It is difficult to judge the measurement since it is instantaneous. hence we should be estimating which is not very accurate.
Improvement : Record the experiment with a camera and use slow motion playback to record measurements as accurately as possible.

Hope it helps ;)

Thank you :)
Title: Re: AS Phys Prac Errors & Improvements
Post by: Deadly_king on October 25, 2010, 05:05:23 am
Repeat the experiment ?

When measuring things use a measuring apparatus with a lower uncertainty.

Indeed lower uncertainty is a good point, but usually you don't get sophisticated apparatus in a lab. So you could just change the words but still use the same reasoning.

Example : If you're measuring the period of oscillation. Instead of saying, use a stopwatch with lower uncertainty(which is not very likely to be available), you could say, measure for a longer time,i.e larger number of oscillations.

Hence an increase in the time would reduce uncertainty ;)
Title: Re: AS Phys Prac Errors & Improvements
Post by: Chingoo on October 25, 2010, 02:48:22 pm
A tip to remember is that accuracy depends upon systematic error while precision depends upon random error. Furthermore, systematic error has a constant sign and magnitude and random error has a varying sign and magnitude. When you're asked in the examination to pick out the errors and then provide symmetric improvements, keep in mind which factor is variable and why. This is your random error. DO NOT ever assume a systematic error, because that way you're either implying that you're too big a goof to work a way around the systematic error. Quantities like reaction time, temperature (was the AC on when the practical started, but not later? This is reported by the center so use it to your advantage, but try to remain focused), distance, measurement of extreme position (parallax error?), etc. Good luck!
Title: Re: AS Phys Prac Errors & Improvements
Post by: Deadly_king on October 25, 2010, 03:26:18 pm
A tip to remember is that accuracy depends upon systematic error while precision depends upon random error. Furthermore, systematic error has a constant sign and magnitude and random error has a varying sign and magnitude. When you're asked in the examination to pick out the errors and then provide symmetric improvements, keep in mind which factor is variable and why. This is your random error. DO NOT ever assume a systematic error, because that way you're either implying that you're too big a goof to work a way around the systematic error. Quantities like reaction time, temperature (was the AC on when the practical started, but not later? This is reported by the center so use it to your advantage, but try to remain focused), distance, measurement of extreme position (parallax error?), etc. Good luck!

Hehe.......thanks for the advice dear :D

+rep
Title: Re: AS Phys Prac Errors & Improvements
Post by: lana on October 26, 2010, 02:49:07 pm
has anyone done the paper yet ??
Title: Re: AS Phys Prac Errors & Improvements
Post by: elemis on October 26, 2010, 03:04:43 pm
has anyone done the paper yet ??

Yeah.
Title: Re: AS Phys Prac Errors & Improvements
Post by: Deadly_king on October 26, 2010, 03:10:32 pm
has anyone done the paper yet ??

I think some people sat for it today.............so you need to wait for 24 hours before having any discussions about it ;)

A little bit patient dear :D