Ch. 21 Electromagnetic Induction and Faraday's Law

What is an induced EMF?

• voltage generated from a changing magnetic field that causes a current

In an induced EMF, what matters the most?

• relative motion..

  • of coil and magnet

Define magnetic flux

basically how much magnetic field passes through a given field

What is Faraday’s Law of Induction?

• induced EMF = (proportional) rate of change of magnetic flux through a loop

True or False: When the flux changes it induces the voltage through an area per time

True

True or false: The more loops there are will cause a decrease in voltage according to Faraday’s Law of Induction.

False

• The more loops there are will cause an INCREASE in voltage according to Faraday’s Law of Induction.

When the flux changes it _________ a voltage.

When the flux changes it INDUCES a voltage.

Magnetic flux will change if the angle between __________ and the _______ change

Magnetic flux will change if the angle between THE LOOP and the FIELD change

What is Lenz’s Law?

(-) sign

• states direction of the induced EMF (current always opposing the change in magnetic flux)

If the magnetic flux is increasing, decreasing, or at zero, in what direction is the flux going/what is it doing?

• opposite direction to og field = flux increasing

• same direction = flux decreasing

• zero change = no flux change

What are the steps to solving a Lenz’s Law problem?

1. determine whether magnetic flux is inc/dec/unchanged

2. determine the direction of magnetic field (RRH)

What happens when a conductor moves through a magnetic field?

an EMF is generated w/in a closed loop

• conductor (length + speed)

when a conductor moves throughout a magnetic field, what happens to the electrons?

• experience a force

  • charge separates

    • cause a voltage!! /induce current (slow the moving bar)

True/False: Changing a magnetic flux produces an electric field

True

Generators convert _______ energy to ______ energy

Generators convert MECHANICAL energy to ELECTRICAL energy

What are the most common type of generators

AC

True or False: less switches in a generator indicate the presence of an DC.

False

• more switches….