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First Five
 Silently enter the room and sit down in your
assigned seat.
 Begin working on your Activator.
 When you’ve completed your Activator, read your
DEAR book.
Today’s Objectives
 SWBAT explain identify ways to increase the
strength of an electromagnet in order to describe the
structure and function of an electromagnet.
 When electric current (moving electrons) is passed
through wire, a magnetic field is formed around the
wire
 The production of a magnetic field by electric current
is called electromagnetism.
Right Hand Grip Rule
Thumb – direction of current
Fingers – direction of magnetic field produced
• A solenoid is a coil of wire that
produces a magnetic field when
carrying an electric current.
• The electricity is what produces the
magnetic field
 A magnet that is made by passing an electric current
through a wire (in the form of a solenoid) wrapped
around an iron core is called an electromagnet.
 While current flows, the core behaves like a magnet
 But, as soon as the current stops, the magnetic
properties are lost.
The Magnetic Field of an Electromagnet
 The magnetic field produced
around the wire is similar to that
surrounding a bar magnet.
 The magnetic south pole is where
the current (abbreviated by I) goes
in and the magnetic north pole is
where it exits in the wire coil
 Just like in all magnets, the
direction of the field still moves
from north to south
Ways to Increase the Strength of an
Electromagnet
1) Increasing the current running through the
solenoid (which can be done by increasing the
voltage of the electrical source or by)
A.
One way to increase the voltage is to add another battery
2) Placing an iron core at the center of the coil
3) Increasing the number of coils of the wire or
solenoid
4) Increasing the thickness of the wire coil
Advantages of electromagnets
• Turning Electromagnets On and Off
Electromagnets are very useful because they
can be turned on and off as needed. The
solenoid has a field only when there is
electric current in it.
• Changing Polarity
Electromagnets are also very useful to
change polarity (north pole becomes south
pole)
Electromagnetism
Anything that uses electricity or a motor most likely
uses electromagnetism.
Everybody Writes
 A magnet can be made by wrapping a
_______into a coil and attaching the ends of the
wire to the terminals of a battery cell. This magnet
is called a(n)______________________.
 The strength of an electromagnet is affected by the
number of ______ in the wire.
 The strength of an electromagnet is affected by the
amount of electrical ___________ in the wire.
 The strength of an electromagnet is affected by the
material (core) the wire is wrapped around. This
core is most likely made of _________.