# Physics Paper 5 tips

#### hateexamz

cn anyone teach me how to draw error bars??? btw how do we noe that the bar to be drawn is vertical or horizontal??

#### h.alia

cn anyone teach me how to draw error bars??? btw how do we noe that the bar to be drawn is vertical or horizontal??
to add error bars to a point on a graph , simply take the uncertinaty range ( expressed as +/- its value ) and draw lines of a corresponding size above and below or on each side of the point depending on the axis to which the value corresponds

#### hateexamz

to add error bars to a point on a graph , simply take the uncertinaty range ( expressed as +/- its value ) and draw lines of a corresponding size above and below or on each side of the point depending on the axis to which the value corresponds
so if the uncertainities are of the values corresponding to y axis the error bars would be vertical??

#### h.alia

so if the uncertainities are of the values corresponding to y axis the error bars would be vertical??
yups

#### smzimran

so if the uncertainities are of the values corresponding to y axis the error bars would be vertical??
If the uncertainties are given for a quantity that is to be plotted on x-axis, error bars will be horizontal.

If the uncertainties are given for a quantity that is to be plotted on y-axis, error bars will be vertical.

#### Sky8

If we use signal generator , do we have to use alternating power supply ?

#### thunderingthunder

Can anyone help me with hall probe?
How do we use it to measure the magnetic flux density?????

#### talha970

Assalamoalaikum wr wb!

say you are taking log of x...
now x is suppose.. 83 +/- 5...
log 83 = 1.92
so Upper Limit (UL) = 83 + 5 = 88
and lower limit (LL) = 83 - 5 = 78
find log of (UL-LL)/2 = (88-78)/2 = 5
log 5 = 0.70 => This is the uncertainty...
so log(83 +/- 5) = 1.92 +/- 0.70

Sorrydid a mistake in the metod I mentioned ealier...
this is how we proceed..
[log(UL) - log (LL)]/2

Check smzimran's post below..he has a different method...
this is the way we were taught...

Hope this helped..!
or you could do it this way e.g R=1.7+/- 0.2 then uncertainty in logR would be (deltaR/R*In10)

#### shyqueen

Can anyone help me with hall probe?
How do we use it to measure the magnetic flux density?????
i asked my teacher da same ques n my teacher said dat v dont need to write about how hall probe works we jus gotta knw it is a device used to measure magnetic flux density n yu can draw a square shaped box showing it is a hallprob n connect it wit a voltmeter dats all i knw.

#### angelicsuccubus

Experiments that have been asked to be designed so far:
1. investigating the terminal velocity of a steel ball dropped in oil and it's relation to the radius
2. determining the resistivity of glass
3. determining the Young modulus of wood
4. investigating the relation between the depth of a nail being hammered into wood and the speed with which it's hammered (jobless much?)
5. determining the absorbtion coefficient of glass
6. investigating the relation between the amplitude of a sound wave and the air pressure inside a double-glazed window
7. investigating the relation between the resistance of an LDR with the distance from the light source
8. investigating the relation the volume of air in a bottle and its resonant frequency
9. investigating how the emf in a coil Y depends on the frequency of the current in coil X
10. investigating the reltion between the strength of the magnetic field and the radius of the coil, using a hall probe
I didn't go through all the variants so someone else can add to the list.

#### user

AsSalamoAlaikum Wr Wb!

Came across an important note [atleast I am reading this for the first time], so wanted to share it with you all.

Rounding errors were also made. A number of candidates only used one decimal place for lg d. It is expected that the number of significant figures in calculated quantities should be the same or one more that the number of significant figures in the raw data; however, in logarithmic quantities the number of significant figures is determined by the number of decimal places. In this question, since d was given to two significant figures, it was expected that lg d should have been given to either 2 or 3 decimal places.

^extract from June:2009 Examiner Report, Paper 5.

#### smzimran

AsSalamoAlaikum Wr Wb!

Came across an important note [atleast I am reading this for the first time], so wanted to share it with you all.

Rounding errors were also made. A number of candidates only used one decimal place for lg d. It is expected that the number of significant figures in calculated quantities should be the same or one more that the number of significant figures in the raw data; however, in logarithmic quantities the number of significant figures is determined by the number of decimal places. In this question, since d was given to two significant figures, it was expected that lg d should have been given to either 2 or 3 decimal places.

^extract from June:2009 Examiner Report, Paper 5.

I always write the data to one better s.f than given !
JazakAllah khair for reminding,
May Allah bless you!
Ameen

#### user

I always write the data to one better s.f than given !
JazakAllah khair for reminding,
May Allah bless you!
Ameen
the point to note is...if it's log, then instead of sf, we go for the dp! like if it was 2sf in the raw data [note it was zero decimal places in that case], we put our data either 2 dp or 3 dp (one better)

Aameen
wa eyyakum
may Allah bless u too..

#### angelicsuccubus

did you guys make any diagrams for the experiment planning while solving pastpapers? If yes, please put some pictures up.. even just looking at them before entering the exam will help loads!

#### SkyPilotage

the point to note is...if it's log, then instead of sf, we go for the dp! like if it was 2sf in the raw data [note it was zero decimal places in that case], we put our data either 2 dp or 3 dp (one better)

Aameen
wa eyyakum
may Allah bless u too..
Yes for logarithms, the number of s.f determine the number of d.p.
If x = 5 s.f ( disregard d.p ) then log (x) --> 5 or 6 D.P!
Anyways thanks for noting and reminding others!
Jazak Allah

#### user

Yes for logarithms, the number of s.f determine the number of d.p.
If x = 5 s.f ( disregard d.p ) then log (x) --> 5 or 6 D.P!
Anyways thanks for noting and reminding others!
Jazak Allah
wa eyyakum..
i didnt know this point before

#### SkyPilotage

wa eyyakum..
i didnt know this point before
Now you do alhamdulellah!