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Electricity and Magnetism
IPC Spring 2008
Electricity and Magnetism
 1. A magnet is any substance that
can attract iron and other
magnetic materials.
 Examples of magnetic materials
are cobalt, nickel, iron, and alloys
of these metals.
Electricity and Magnetism
 Properties of Magnets:
 a). Ends of a magnet: north pole and south pole
 b). Characteristics of a magnet: like poles repel, unlike
poles attract.
 c). Ways of making a magnet:
 1. Contact (stroking in one direction),
 2. Electricity (contact with flowing electrons)
 3. Induction (not touching another object, but lying in
its magnetic field)
 d). Ways to demagnetize a magnet:
 1. Heating,
 2. Jarring
 3. Rub back and forth with another magnet.
Electricity and Magnetism
 2. The needle of a compass is a
magnet.
 The north pole of the needle is
attracted to the south magnetic
pole of the earth.
 The geographic north pole of the
earth is a magnetic south pole.
Electricity and Magnetism
 3. The area around the magnet where
the magnetic force acts is called the
magnetic field.
 A circular magnetic field is produced
around a wire that is carrying a current.
If the wire is made into a coil, the ends
of the coil become magnetic poles.
 When a wire is moved perpendicularly
through a magnetic field or when a
magnetic field is moved perpendicularly
to a wire, a current is produced in the
wire.
Electricity and Magnetism
 4.
An electromagnet is a currentcarrying coil of wire around an iron core.
 The magnetic field of the coil and the
magnetic field of the iron core combine
to produce a stronger magnetic field.
 The strength of an electromagnet can be
increased by increasing the current or
increasing the number of turns in the
coil of wire.
 Examples of electromagnets are:
generators, transformers, and
electric motors.
Electricity and Magnetism
 5. Electricity is a form of energy that
deals with the movement of electrons.
 The three forms of electricity are:



a. static electricity - the net
accumulation of electric charges on an
object,
b. current electricity - the flow of
electrons in a circuit
c. magnetism - the attraction and
repulsion between magnetic poles
Electricity and Magnetism
 6. Atoms contain electrically
charged particles called protons
and electrons.
 Protons
have a positive charged.
 Electrons have a negative charge.
 Their charges are equal and
opposite.
Electricity and Magnetism
 7.Two different uncharged objects can
become electrically charged when they
are rubbed against each other.
 Electrons can be lost by one object and
gained by the other.
 Each object no longer has equal
numbers of protons and electrons.
 ***NOTE: only the electron (-) moves.
Electricity and Magnetism
 8. An object that has more electrons
than protons is said to be negatively
charged.
 An object that has fewer electrons than
protons is said to be positively
charged.
 If the positive charges equal the
negative charges, there is no net
charge on the object (neutral charge).

Electricity and Magnetism
 9. Objects with like charges repel and
objects with unlike charges attract.
 10. A conductor is a substance that
allows an electric charge to flow
through it easily.
 An insulator does not allow the easy
flow of electric charge through it.
Electricity and Magnetism
 11.A simple electric circuit is made up
of a voltage source, a conductor and a
load.

 12.Direct current is defined as flowing
from the negative terminal to the
positive terminal.
 Alternating current is the type of
current that changes direction at regular
intervals in a circuit. AC is produced by
generators. In this country it switches
60 times per second.
Electricity and Magnetism
 13.An electric circuit in which the
current flows in a complete path is
called a closed circuit.
 An electric circuit that is broken
somewhere along the current's
path is called an open circuit.
Electricity and Magnetism
 14.A system through which an electric
current can travel is called an electric
circuit.
 Electric current is the flow of electrons.
 Electric current is measured in units
called amperes, or amps (a).
 Potential difference, or voltage, is a
measure of the energy available to
move charges in a circuit. Potential
difference is measured in volts (V).
Electricity and Magnetism
 The common American household
voltage is 110 V.
 The opposition to the flow of
charges in a substance is called
resistance.
 Resistance is measured in units
called ohms (Ω).
Electricity and Magnetism
 15. A schematic diagram is a
drawing of an electrical circuit using
symbols.
 Schematic diagrams can be used to
represent series and parallel circuits.
 Note: In a battery symbol: the whole line
represents 1 volt. The half line represents a
half a volt. So, this
represents 1.5 volts.
A cell is 1.5 volts as shown here.
Electricity and Magnetism
 16.A series circuit has only one path
for the current.
 A parallel circuit has more than one
path for the current.
 NOTE: A parallel circuit offers less
resistance than a series circuit because
each electron does not have to travel
through each resistance: they take
their own separate path.
 In a series circuit, each electron must
travel through the entire circuit.
Electricity and Magnetism
 17.A voltmeter is a device that
measures the potential difference
between two points in an electric
circuit. It measures in volts. A
voltmeter makes a branch when
connected, in order to measure a
drop in voltage before and after a
resistor (or lamp) in a straight line
with the source of voltage.
Electricity and Magnetism
 An ammeter is a device that
measures the current of an electric
circuit. It measures in amperes.
(amps) An ammeter is not on a
branch by itself, but is always
connected in a line with the source
of voltage.
Electricity and Magnetism
 18.Fuses and circuit breakers
are devices for interrupting the
flow of charges in a circuit. They
are both safety devices that open
an electric circuit.
 Fuses must be replaced and circuit
breakers may be reset.
Electricity and Magnetism
 19. The relationship of resistance,




voltage and current can be written as a
formula, called Ohm's law.
V=IR
or
I=V/R
R stands for resistance and is
measured in ohms ().
V stands for voltage and is measured
in volts.
I stands for current and is measured in
amps.
Electricity and Magnetism
 20. The relationship between
electric power and current is
shown by the following formula

P = VI
 In this formula, P stands for
power and is measured in watts.
V stands for voltage (volts) and I
stands for current (amps).
Electricity and Magnetism
 21. Much of the electricity we use daily
is obtained using fossil fuels, such as
coal, petroleum and natural gas. These
sources of energy are being depleted
and alternative energy sources are
being developed to produce electricity
with greater efficiency. Alternative
energy sources include:
Electricity and Magnetism
 a. solar - accessing energy in
sunlight through the use of solar
panels.
 b. tidal – the inward flow of water
is trapped and the kinetic energy
of the water escaping out is used
to generate current.
Electricity and Magnetism
 c. geothermal – using the
consistent temperature of the
earth to keep homes warm or cool,
or using molten rock rising near
the surface of the earth's crust to
superheat water and turn turbines
in generators that generate
electricity.
Electricity and Magnetism
 d. nuclear – energy released when
atom nuclei are split or fused
 nuclear fission – The splitting of an
atom's nucleus into two nuclei.
Releasing heat that is used to generate
steam and then, electricity.
 Nuclear fusion is not being performed
to generate electricity. In order to force
two smaller nuclei into one larger
nucleus, tremendous temperatures are
required.
Electricity and Magnetism
 e. wind – the motion of air
turning windmills and generators
to generate electricity.
 f. hydroelectricity – available to
communities near major rivers, the
motion of flowing water flowing
through a dam, turns generators
that produce electricity.
Electricity and Magnetism
 22. Common sources for electrical
devices:
 a). disposable batteries
 b). rechargeable batteries
 c). solar cells