Physics Dept. Demonstration Manual

DEM33 - Differentiation by Induction (Elex Lab EM17 using a Function Generator and Oscilloscope)

Objective:

Use a function generator and oscilloscope to demonstrate that for two magnetically linled coils, the induced EMF is the differential of the supplied EMF

 
Apparatus:  
  • 2 Gilley Coils
  • Iron core, Copper core, Aluminum core
  • Digital Oscilloscope (Tektronix TDS 2012C)
  • Function Generator (BK Precision 4011A)
  • 470 ohm limiting resistor
  • Leads


Method:

First input a sine wave, and notice that the output is also a sine wave but phase shifted by 90 degrees. Ask the students to predict what will happen when a square wave is inputted,
then change the input to a square wave and notice the sharp spikes on the output corresponding to the upward and downward edges of the square wave.

This demonstration may also be used to demonstrate the flux linkage between the two coils by substituting the iron core for air, copper and aluminum.

Settings:

Osilloscope

- Channel 1 = 20.0 volts Channel 2 = 20.0 millivolts
- 10.0 ms

Function generator

- set at 400 hertz