Calculations using Experimental Data (Edexcel International A Level Physics)

Revision Note

Katie M


Katie M



Calculations Using Experimental Data

  • Collecting experimental data is only some of the work required when carrying out a practical
  • When setting up a data table, space must always be left for some calculations
  • The most common calculation is the mean for repeat readings

Mean = fraction numerator s u m space o f space t h e space r e a d i n g s over denominator n u m b e r space o f space r e a d i n g s end fraction

  • The value of the mean is then used in for further calculations
    • Anomalous readings should be ignored in this calculation
  • The mean should have the same number of significant figures as the readings used to calculate it

  • The experiment may require to calculate a variable which you can't directly measure
    • E.g., the area of a wire
  • In this case, other measurements are taken, which then by using an equation, the variable that is required can then be calculated
    • E.g., area of a wire = πr2, so r is measured for the wire using a micrometer and substituted into this equation to calculate the corresponding area for each value of r
  • Another example of this is finding the 'log' of a value
    • One column in a data table should be for the measurement
    • A column next to it should be the for the 'log' of that measurement
  • In the Hooke's law experiment, the 'extension' cannot be measured direction, but can be calculated from the final and initial length, which can be measured 

Hooke's Law Table of Results

Table of results

Worked example

A student wants to find the resistivity of a constantan wire. They set up the experiment by attaching one end of the wire to a circuit with a 6.0 V battery and the other with a flying lead and measuring the length with a ruler. Attaching the flying lead onto the wire at different lengths, they obtain the following table of results.

Worked example table 1, downloadable AS & A Level Physics revision notesCalculate the the missing values from the table.

  • The average current is calculated by

fraction numerator I subscript 1 plus I subscript 2 plus I subscript 3 over denominator 3 end fraction

  • The resistance is calculated using the equation

Resistance Equation

  • All readings are to 3 significant figures, so all values calculated should also be to 3 s.f.

Worked example solution table, downloadable AS & A Level Physics revision notes

Exam Tip

These calculations show why it's important not to draw your data tables too big, without leaving space for more columns and rows. Think carefully about what data you need to measure, but also what you may need to calculate in order to draw graphs in the future. Thinking ahead this way will reduce the change of drawing messy tables that you'll have to keep redoing in the exam!

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Katie M

Author: Katie M

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.