Section 2: Magnetic Induction

Magnetic Field Around a WireRight Hand Rule:

Current is in the direction of positive charge flow

Magnetic Fields around Paired Wires

Magnetic Field in a Loop:

Magnetic Field in Solenoid

Electro Magnet

How it works:

What makes a strong electromagnet:1) 2) 3)

Forces on charges:

To find the force:1) Fingers go in the direction of the

field2) Thumb goes in the direction of

the charge3) Palm goes in the direction of

force of a (+) charge and opposite for (-) charge.

Force, Current, and Magnetic FieldsForce on a positive charged particle moving througha magnetic field: F = BqV

Sample Problem: Find the force and direction on a 2C positive charge that is in a 3 T (Tesla) magnetic field and traveling with a velocity of .5m/s

Force on a wire with current in a magnetic field: F = BIL

Sample Problem: Find the force on the 1.5 meter wire that has 2 amps of current passing through it when placed in a 10 T (Tesla) magnetic field.

Electromagnetic Induction: When current is created in a conductor using a changing magnetic field

Factors that affect magnetic induction:1) 2)

Lenz’s Law: The direction of the magnetic field of an induced current oppose the magnetic field that created it.

Faraday’s Law for creating current: Voltage = -NA(ΔB/Δt)

Sample Problem: Find the voltage produced when a coil of wire with 5 turns and a cross section of .002m2 feels a magnetic field change of .4T/s.

Practice Problems

A 52 turn coil with an area of .0055m2 is dropped from a position where the magnetic field strength is zero to a position where the field strength is .55T which occurs in .25s. Find the average emf (induced voltage).

Building an Electric Motor