## PicoScope 5000 Series

#### FlexRes® Oscilloscopes

High speed and high resolution. Breakthrough ADC technology switches from 8 to 16 bits in the same oscilloscope.

# Proving the formulae for series and parallel resistance

## 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 setup

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

## Measuring resistors

Connect the resistor to measure (RMEASURE) to B-1 and B-4 as shown in Figure 1.

Use the Meter function in PicoScope to measure the resistance, note this value, and then repeat using different value resistors.

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.

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.

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” (light bulbs, 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.