Download Magnetism Just the basics Magnetic Poles • Magnetic poles are

Magnetism
Just the basics
Magnetic Poles
• Magnetic poles are LIKE ________________ _________________
• Like poles ________________ and opposite poles ________________.
• They are caused by the movement of ________________ in the atoms of elements
• The two poles are called ________________ and ________________
• All magnets are ________________
• This means that ________________ magnet, ____________________________________,
has ________________ a north pole and a south pole
Magnetic monopoles do not exist!
• If I have a magnet, it has a north and south pole
•
If I cut the magnet in half…

Each half will STILL have ________________________________________________
Magnetic Fields
• Magnetic fields are VERY similar to ________________________________and we draw them the
same way.
• Magnetic field lines are drawn to point away from north and toward south
• The symbol for magnetic field strength is  ________________
• The unit magnetic field strength is measured in is  ________________
Electricity and Magnetism
• Hans Christian Oersted discovered that ANY time there is an ________________
________________ (a moving electron) there is a ________________
________________produced.
• That magnetic field is ________________ to the current.
First Right Hand Rule
• This rule helps us find the direction of the magnetic field around a wire with current flowing
through it.
• Use your right hand
– Point your thumb in the direction of the ________________ ________________.
– The magnetic field wraps around the wire in the direction your fingers curl.
•
Example
Second Right Hand Rule
• This rule is used to find the ________________ of an electromagnet
– Using your Right Hand
– Curl your fingers in the direction of the ________________ ________________and your
thumb will be pointing in the direction of the ________________ _______________
Michael Faraday
• Faraday discovered that when a current carrying wire is placed inside a magnetic field, the
magnetic field will cause a ________________ to be applied to the wire.
• The direction of this force can be found by yet another right hand rule
Third Right Hand Rule
• Used to find the direction of the ________________ acting on a current carrying wire in a
magnetic field
• Using the right hand
– Point your thumb in the direction of the ________________ _______________ and your
index finger in the direction of magnetic field. The force will be in a direction
________________ of your palm.
Pictures of the right hand rules (in order)
Electromagnetic Induction
• Oersted discovered that an electric current causes a magnetic field.
• Faraday discovered that if a wire is moved while in a magnetic field, then the magnetic field will
cause (induce) an electric current.
• This is how electric ________________ work
– Most of the time however, we move the ________________ instead of the
________________
– It is also how ________________ ________________ ________________work
Alternating Current
• When a magnet is spun inside of a coil of wire in a generator, the ________________ of the north
and south pole is ________________ changing.
• This causes the direction of the current induced in the wire to change
– This is called ________________ ________________ ________________
Electric Transformers
• Transformers are devices that use electromagnetic induction to ________________ or
________________ the ________________ in a circuit.
• How much the voltage is stepped up or down depends on the ________________
________________ ________________on each side
Calculating Voltage of a Transformer
• The voltage in the primary and secondary coils have the same ratio as the number of turns in the
coils
• Use the following equation
Example 1
• What is the resulting voltage in the secondary coil of 40 turns if the primary coil has 20 turns and a
voltage of 60V?
Example 2
• I have a circuit with a voltage of 120 V. If I wrap this wire around an iron core 3000 times, how
many times will I need to wrap a second wire to produce a voltage of only 6 V?