Suitable for
Ages 12–19
KS4 KS5
Educational data loggers

Introduction

In electrical circuits, resistance is the property of an electric conductor by which it opposes a flow of electricity and dissipates electrical energy away from the circuit. Using a data logger to measure the resistance, the aim of this experiment is to prove the formulae used for calculating series and parallel resistance, and introduce the concept of electron flow through the different paths of an electrical circuit.

Equipment required

  • DrDAQ data logger
  • Various resistors of different values
  • Small terminal block (optional)

Experiment set up

  1. Connect the DrDaq data logger to a PC
  2. Attach the DrDaq 'R' connector to terminal board side A-1
  3. Attach the DrDaq 'G' connector to terminal board side A-4

Method

Measuring resistors

  1. Connect the resistor to measure (R_MEASURE) to B-1 and B-4 as shown in Figure 1.
  2. Use the Meter function in PicoScope to measure the resistance, note this value, and then repeat using different value resistors.
Measuring resistance using DrDAQ

Figure 1

Measuring resistors in series

  1. Connect the resistors to measure (R1 and R2) to B-1 and B-2, and B-3 and B-4 as shown in Figure 2.
  2. Connect a wire from A-2 to A-3 as shown in Figure 2.
  3. Once again use PicoScope to measure the resistance, note this value, and then repeat using different value resistors.
Measuring series resistance using DrDAQ

Figure 2

Measuring resistors in parallel

  1. Connect the resistors to measure (R1 and R2) to B-1 and B-4 as shown in Figure 3.
  2. Use PicoScope to measure the resistance, note this value, and then repeat using different value resistors.
Measuring parallel resistance using DrDAQ

Figure 3

Questions and discussion of the results

  • Why is the resistance lower when the resistors are connected in parallel?
  • Why is the resistance higher when the resistors are connected in series?
  • What is a benefit of connecting “loads” (lightbulbs, motors,etc) in series? / Parallel?

Further study

  • Connect up more resistors in series and in parallel to see what the results will be.
  • Think of suitable applications for a device that is able to sense resistance values.

Credits, comments and further info

Thanks to Mrs. Bowen’s 5th & 6th grade science classes from the Covenant Christian School in Florida,USA for submitting this experiment.