Electromagnetism - experiments with a simple AC dynamo

Introduction

This educational application note shows how the output of a simple AC dynamo can be displayed using a PC Oscilloscope. It assumes a basic knowledge of electromagnetic induction. 

Equipment required

• Simple AC Dynamo
• A Pico PC Oscilloscope (We used a dual-channel channel PicoScope 2205)
• Connecting cable, Pico part number MI029
• Supplied USB cable from the 2205 to your PC or laptop

Any dynamo is suitable for these experiments. 

Experiment setup

The experiment was set up as shown in the photograph below.

Analyzing the results

To test the setup, the handle was given a few turns. The PicoScope oscilloscope software was set to single-shot trigger to capture the results. Pre-trigger (40%) was used to show signals before and after the trigger event. The PicoScope screen shot shows the results:

Example questions

1. What was the maximum frequency produced by the dynamo?
2. What was the maximum voltage it produced?
3. What happened to the speed of rotation of the dynamo while it was turning?
4. How was the voltage related to the the speed of rotation of the dynamo? Use your knowledge of electromagnetic induction to explain this.