Methods to Increase Accuracy | OCR A Level Physics Revision Notes 2017 (2024)

• The accuracy of an experiment can be increased by repeating measurements and using mean values
• Methods seeking to reduce systematic errors result in increased accuracy
• In order to reduce the uncertainty of results for an experiment some changes may need to be made to the method, such as:
  • Timing over multiple oscillations
  • Using a fiducial marker
  • Using a set square or plumb line

Using Multiple Oscillations

• Uncertainty in a measurement of periodic time can be reduced by:
  • Measuring many oscillations to calculate the average time for one oscillation
  • Increasing the total time measured for multiple swings
• It would be ideal to measure the time taken for the pendulum to complete 10 (or more) oscillations and divide this time by 10 to determine the time period of one oscillation

One complete oscillation of a pendulum

Fiducial Marker

• A fiducial marker is a useful tool to act as a clear reference point, such as when measuring time period of a pendulum using a stopwatch
• This improves the accuracy of a measurement of periodic time by:
  • Making timings by sighting the pendulum as it passes the fiducial marker
  • Sighting the pendulum as it passes the fiducial marker at its highest speed. The pendulum swings fastest at its lowest point and slowest at the top of each swing

A fiducial marker is used to mark the centre of the oscillation of the pendulum

Set Squares & Plumb Lines

• A set square can be used to determine whether:
  • An object is vertical
  • Two objects are at right angles to each other
  • Two lines are parallel
• A plumb line can be also be used to determine if a setup is vertically aligned accurately

A plumb line and set square used to make sure the setup is completely vertical