DrDAQ is a versatile instrument that connects to the USB port of any PC. Using the supplied PicoScope software it can be used as an oscilloscope, spectrum analyzer and signal generator.
This experiment investigates magnetic induction, as governed by Faraday’s First Law:
When the magnetic flux threading a circut is changing, an E.M.F. is induced in the circut.
The experiment involves dropping a magnet through a coil of wire and observing the result on a PC-based oscilloscope.
To perform this experiment with DrDAQ we have to use the custom ranges feature in PicoScope. To do this a file can be installed into PicoScope or the settings can be entered manually. Both are explained below.
Q1. Why are both negative and positive voltages generated as the magnet passes through the coil?
Q2. Why does the width (duration) of the pulse vary as the coil is moved up and down the tube?
Q3. What is the relationship between the speed of the magnet, as it travels through the coil, and the amplitude of the voltage produced from the coil?
Q4. What happens to the speed of the magnet as it passes through the coil?
Due to the small distance from the release point of the magnet to the top of the coil, the pulse produced by the induced E.M.F is asymmetric. The pulse only becomes truly symmetrical when the distance between the coil and the release point of the magnet is large. Why is this effect seen?
Measure the distance between the magnet's release point and the coil, use this to calculate the velocity. Repeat this for different distances and plot a graph of peak amplitude versus magnet velocity.
Use Lenz’s law to explain how the polarity of the magnet affects the direction of the induced current.