Physics 2225: Faraday’s Law Purpose Study the induction of electric current according to Faraday’s Law.

Physics 2225: Faraday’s Law

Purpose

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

Physics 2225: 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.

Physics 2225: Faraday’s Law

Magnetic Flux Through a Loop of Wire

cosABB

Cross sectional areaof the loop

B

Physics 2225: Faraday’s Law

An Example of Induced Voltage

e

B

e

B

090cos, ABinitialBABABfinalB 0cos,

Time it took to rotate coil by 90: Dt

t

BA

ttinitialBfinalBB

average

,,

Physics 2225: Faraday’s Law

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.

Physics 2225: Faraday’s Law

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.

Physics 2225: Faraday’s Law

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.

Physics 2225: Faraday’s Law

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

Physics 2225: Faraday’s Law

Activity 3: Replacing Field Coil with Small Coil

Signal generator output

Physics 2225: Faraday’s Law

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.