Purpose

Physics 2225: Faraday’s Law

Purpose

• Study the induction of electric current according to Faraday’s Law.


Faraday’s Law

tB

Induced electromotive Force (“voltage”)

Change in the magnetic fluxthrough the loop

Time interval over whichthe flux change occurs.


Magnetic Flux Through a Loop of Wire

cosABB

Cross sectional areaof the loop

B


An Example of Induced Voltage

B

B

090cos, ABinitialBABABfinalB 0cos,

Time it took to rotate coil by 90: t

tBA

ttinitialBfinalBB

average

,,


Activity 1: Flux Change by Moving Magnet

LED

Plug LED connector into2000 turn detector coil

LED light turns green or red, depending onthe polarity of thevoltage.


Activity 1: Flux Change by Moving Magnet

Cow magnet

Move cow magnet EXTREMELY QUICKLYin and out of the detector coil.Watch color of LED duringmovement.


Activity 2: Flux Change Using Function Generator

Function Generator

200 turn field coil: Called “field” coil because it is used to generate a magnetic field by running current through it.

An alternating current (from function generator)creates an alternating magnetic field by thiscoil.


Activity 2: Flux Change Using Function Generator: Setup

BNC T-piece

Signal generator output

BNC to Banana adapter

“Banana” cables

Ch 1: Monitors signalfrom signal generator(and thus the B-fieldgenerated by thefield coil).

Ch 2: Monitors the voltage induced inthe detector coil.

Now you can compare thesetwo on the two oscilloscopechannels

Don’t use middleconnector


Activity 3: Replacing Field Coil with Small Coil

Signal generator output


Activity 4: Flux Change by Moving Magnet, Observed with Oscilloscope

Plug both BNC cable and LED into the detector coil

Similar to Activity 1, but also monitor voltage with Ch. 1 of oscilloscope.

Set timescale to 500ms,vertical scale as needed.

Documents

Purpose