Electricity
Lesson 1 How Are Electricity and Magnetism Related?
Electricity
Recall that atoms contain charged particles.
A proton has a p_____________________ charge.
An electron has a n_____________________ charge.
An atom can have m_________ electrons than protons.
This gives the atom a n________________ charge.
An atom with more protons than electrons has a p_____________ charge.
Atoms with o________________ charges attract each other.
In an atom, electrons move around o________________ the nucleus.
In some elements, electrons can also move from one atom to another.
This m________________ of e________________ p________________
e________________.
Electricity(DEFINE):___________________________________________________
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Lamps change electricity into l________________ energy.
Electricity changes to motion, or m________________ energy.
Electricity can also change to h________________ energy.
What do a doorbell and a radio have in common?
They both use electricity to produce s________________ energy.
MAIN IDEA AND DETAILS: What are four kinds of energy that electricity
can be changed into?
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Electricity and Magnetism
An electromagnet:____________________________________________________
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When electricity flows through a wire, the wire has a m______________
f______________ around it.
A single wire doesn’t have a strong magnetic field.
Winding the wire into a c_____________ makes the magnetic field stronger. Each
t________________ of the wire makes the field s________________.
Electromagnets are useful because they can be turned on and off.
You have seen that e________________ can produce m________________.
This also works the other way around—a m________________ can produce
e________________.
MAIN IDEA AND DETAILS: What are some ways in which electromagnets
are used?
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Electric Motors
You know that e________________ can be changed to m________________
e________________.
The motion of an electric device is produced by an e________________
m________________.
The electric motor is the opposite of a generator that produces electricity in an
energy station.
A motor contains a c________________ of w________________ that can
s________________ inside the m________________ f________________ of a
permanent magnet.
When the motor is switched on, electricity produces a magnetic field in the coil of
wire.
The c________________ becomes an e________________.
The poles of this electromagnet are attracted and repelled by the poles of the
permanent magnet.
This causes the electromagnet to spin.
The motion of the spinning coil can turn the blades of the blender or the fan.
MAIN IDEA AND DETAILS: What are the two main parts of a motor?
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Lesson 2 What Are Static and Current Electricity?
Static Electricity
Most objects have no charge. The atoms making up the matter are
n______________________. They have equal numbers of protons and electrons.
But when one object rubs against another, electrons move from atoms of one
object to atoms of the other object. The numbers of protons and electrons in the
atoms are no longer equal. The objects become either p_____________________
or n______________________ charged. The buildup of charges on an object is
called s______________________ e______________________.
O______________________ charges a______________________ each
other.
When objects with opposite charges get close, e______________________
sometimes j________________ from the n______________________ object to the
p______________________ object. This evens out the charges, and the objects
become neutral.
CAUSE AND EFFECT What causes an object to build up a static charge?
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Current Electricity
For electricity to be a useful source of energy, it must be a
s_______________ f____________ of charges. If electrons have a path to follow,
they will move in a steady flow instead of building up a static charge. This
f____________ of e___________________ is called an e_________________
c__________________ . Electricity that flows in this way is a kind of kinetic
energy called current electricity. To keep the charges flowing, a
c__________________ supply of e________________ is needed.
Electrical pressure forces current through the wires, giving the electrons
energy. This e______________________ p______________________ is
measured in v_________________.
The rate at which electric current flows is measured in a_________. The
combination of volts and amps can be dangerous, which is why many objects that
use electricity have warning labels.
The amount of electrical energy a device uses each second is measured
in w_____________. A label on a hair dryer, light bulb, or clock shows how many
watts it uses. One kilowatt is equal to 1,000 watts.
CAUSE AND EFFECT What causes an electric current to keep moving?
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Conductors and Insulators
Electricity moves more e______________ through some kinds of matter than
others. A material through which electricity moves well is a c______________ .
Most metals are conductors. The electrons of m_____________ are held loosely by
the atoms. This makes it e____________ for the electrons to move between atoms,
causing current to flow.
P______________________ doesn’t conduct electricity well. Its electrons are
n__________ free to move between atoms. A material that conducts electricity
p______________________ is an i______________________ . Wood, glass, and
rubber are also insulators.
Insulators are important because they p______________________ you from
the electric current in the wire. If the layer of plastic on a wire peels off or cracks,
the w______________ s_______________ be r_______________. If you touch a
bare wire that is conducting current, the current will flow through you and
c______________________ h____________ you. Also, wires get warm when
they carry electricity. A bare wire that touches paper or cloth could start a fire.
CAUSE AND EFFECT What causes a metal to be a good conductor?
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Lesson 3: What are Electric Circuits?
Series Circuits
The wires give the e__________________ a path to follow. The path an
electric current follows is called an electric circuit.
An electric circuit needs t______ things for current to flow. First, it needs a
s__________________ of current, or electrons.
Second, the circuit has to be c__________________. If there is a
b__________________ in the circuit, the current won’t flow.
A battery, wires, and light bulbs can form a complete circuit.
A s__________________ controls the flow of current by
o__________________ and c__________________ the circuit. When the switch is
on, the circuit is complete. The light comes on. When you turn the switch off, a
piece of metal inside the switch moves. This b__________________ the flow of
current, and the light goes out.
In a series circuit, the current has only o__________________ path to
follow. The parts are connected one after the other in a s__________________
l__________________. Removing any part of the circuit breaks the circuit, and
current s__________________ flowing.
MAIN IDEA AND DETAILS What two things are needed in order for
current to flow in a circuit?
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Parallel Circuits
Instead of giving the current only one path, you can make a path for
e__________________ d__________________ in the circuit. A circuit that has
m__________________ t__________________ one path for current to follow is
called a p__________________ c__________________.
In a parallel circuit, if one device is turned o______ or r________________,
current stops flowing along the loop f_______ t__________
d_________________. But current c__________________ to f________________
through the rest of the circuit. The other devices don’t stop working. This makes a
parallel circuit m____________ p_________________ to use than a series circuit.
A parallel circuit has another advantage over a series circuit. You can
connect m_______________ d________________ in a parallel circuit. If you
connect too many light bulbs in a series circuit, they all become dimmer. That’s
why old signs wired in series circuits didn’t have many bulbs. But in a parallel
circuit, adding more bulbs doesn’t change how bright they are.
MAIN IDEA AND DETAILS What are two advantages that parallel
circuits have over series circuits? ____________________________________
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Drawing Circuits
You have learned that d__________________ that use
e__________________ have c__________________ inside them. Engineers
design these circuits. Some circuits, such as those in a blender or a lamp, are
simple. Some, such as those in a car or an airplane, are m__________________
c__________________.
When engineers work on a new design, they don’t begin by connecting a lot
of wires. Instead, they draw diagrams of the circuits they will use. Circuit diagrams
use s__________________ to show the p__________________ of a
c__________________. Each part of a circuit has a d__________________
s__________________.
A diagram of the series circuit you built in the Investigate would have
symbols for the b__________________, the w__________________, and the
t__________________ lights. These symbols would be connected in a
s__________________ l__________________.
MAIN IDEA AND DETAILS What do you see on a circuit diagram?
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