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Electromagnetic Induction
THE MAGNETIC FORCE ON MOVING CHARGE
THE NORTHEN LIGHTS
QS.
1- Where does the northern lights happen ?
 2-Where does the magnetic field of Erath very
strong ?
 3- How does the northern lights occur ?
 4- F = B Q v , what does the equation mean ?
 5- In which direction does the force act ?
Look pg :224-226

FLEMING’S LEFT –HAND RULE
WHAT IS ELECTROMAGNETIC INDUCTION ?
When does the pointer of ammeter move ?
WHY DOES ELECTROMAGNETIC INDUCTION
OCCUR ?
Electromagnetic induction. The direction of the induced current is
perpendicular both to the magnetic lines of force and to the direction in
which the wire is moving. No current is induced when the wire is at rest.
USEFUL WEBSITE
http://nuweb.neu.edu/bmaheswaran/phyu121 
/data/ch05/fig05.htm
FARADAY’S MODEL ELECTROMAGNETIC
INDUCTION :

1- what happens when you move the magnet
into coil ?
What happens if you move the coil instead of
the magnet ?
 http://www.bbc.co.uk/scotland/learning/bitesi
ze/standard/physics/energy_matters/source_t
o_consumer_rev1.shtml


What is the relation between the turns of wire
in coil and E.M.F.?

The more turns on the coil , the greater the
e.m.f. this is because N turns will cut N times
more lines of flux than just one turn .

How can you increase the size of the e.m.f.
induced across a coil ?
Useful information

Magnetic flux is the amount of magnetic field threading or “flowing through”
a certain area A, such as the area inside a flat coil of wire. This is
represented diagrammatically by the total number of magnetic flux lines
that pass through area A.

The stronger the magnetic field at a point, the higher the magnetic flux
density B is at that point and the more magnetic flux lines there are cutting
or threading a given area. B is a measure of magnetic flux per unit area
perpendicular to the direction of the field at a point in the field.

To find the total amount of flux passing through area A, we need to multiply
the magnetic flux density B by the number of square meters in area A. This
can be expressed mathematically as flux = flux density × area, or

In SI units, magnetic flux is measured in Webers (Wb) and magnetic flux
density is measured in Webers per square meter (Wb m-2)