TABLE OF VALUES
You must measure the diameter of the wire 3 times to calculate average
Don’t measure diameter once. Uncertainty of micrometer screw gauge…………….
Calculate Area
(L ± 0.1)/cm
(V ± 0.1)/V
(I ± 0.1) mA
(R / Ω)
IMPORTANT NOTES
 Every value in the Length, Resistance, Voltage and Current column must have 1 decimal place
e.g 20 is wrong it must be 20.0
 Don’t put units to you values because the units already exist in the column heading
 Every heading must be written as it is do remove units and uncertainty
 When calculating resistance change I from mA to A
 There is no uncertainty on the heading of R
This is because the uncertainty changes
The uncertainty is calculated for each row
𝑉
𝑅=
𝐼
R
𝑅
=
V
𝑉
R = (
+
V
𝑉
I
𝐼
+
I
𝐼
)x R
use this formula to calculate value of uncertainty in R
So after every value of R in the table put uncertainty
kenias@students.uz.ac.zw
078 204 8887
Justify the number of significant figures for R
What does this question means?
The question is asking you to explain why you have given your R with the significant figures in
the table
We have calculated R using V and I
So the number of significant figures for R must comply with significant figures for V and I
ANS: Number of significant figures for R is equal to the number of significant figures of V or I
GRAPHICAL WORK and CALCULATIONS FOR QUESTION 2
You must use a scale that covers three quarters of the graph page
CHECK IF THERE IS A QUESTION THAT REQUIRES UNCERTAINTY OF GRADIENT
Kan question yacho iripo: Put error bars for each plotted point
Kana question yacho isipo : Don’t put error bars
Each axis must be labeled with the correct units
𝑦 𝑎𝑥𝑖𝑠 𝑙𝑎𝑏𝑒𝑙𝑙𝑒𝑑: R / Ω
𝑥 𝑎𝑥𝑖𝑠 𝑙𝑎𝑏𝑒𝑙𝑙𝑒𝑑: 𝐿/𝑐𝑚
Gradient Calculation
Find two points that are far apart from each other. Don’t use plotted points
Your gradient must have units
Units of gradient = R/cm
Theory suggests that 𝑅 = 𝜌
𝐿
𝐴
.Use your graph to find β and its uncertainty
𝜌 = 𝐺𝑟𝑎𝑑𝑖𝑒𝑛𝑡
The uncertainty of 𝜌 = 𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 𝑜𝑓 𝑙𝑖𝑛𝑒 𝑜𝑓 𝑏𝑒𝑠𝑡 𝑓𝑖𝑡 − 𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 𝑜𝑓 𝑙𝑖𝑛𝑒 𝑜𝑓 𝑤𝑜𝑟𝑠𝑡 𝑓𝑖𝑡
kenias@students.uz.ac.zw
078 204 8887
EXAMPLE OF A GRAPH ERROR BARS
kenias@students.uz.ac.zw
078 204 8887