Download Lesson 1: What is Motion

Name: _____________________________ Date: _____________
Science Notes: Unit 3: Chapter 5
Electricity
Lesson 1: How do electric charges flow in a circuit?

electric current- an electric charge in motion
o An electric current flows quickly and invisibly from one place to
another.
o An electric current flows though some kinds of atoms more
easily than others.
 Most atoms have three different particles.
 Some particles have a positive charge (+).
 Some particles have a negative charge (-).
 Some particles have no charge.
 Matter usually has the same number of positive and
negative particles.
 Static electricity happens when positive and negative
charges no longer balance.
o Other materials do not allow an electric current to move
easily through them.

conductor- material through which an electric charge can move easily
o Most metals, such as copper, gold, and silver, are good
conductors. Metal scissors and the lead (graphite) in pencils
are good conductors too.

insulator- a material through which an electric charge moves with
difficulty
o Plastic, rubber, glass, and dry wood are good insulators. Other
examples of insulators are the eraser on your pencil and chalk
you may use to draw.

circuit- a type of loop that electric charges must complete for a
current to flow
o A current cannot flow if the circuit has any gaps, or breaks.
 A cut wire and an off switch are examples of breaks.
o A circuit is open if it has at least one break.
o A circuit is closed if it has no breaks.
o A circuit has many parts.
Name: _____________________________ Date: _____________
Science Notes: Unit 3: Chapter 5
Electricity

These parts include an energy source such as batteries
or electrical outlets, a wire through which the charges
flow, resistors such as light bulbs or machines, and
sometimes a switch.
Types of Circuits: (See pictures on p. 156-157 of your book.)
 series circuit- an electric charge can flow in only one circular path
o When the power source is turned on, the charged particles in
the wire flow in one direction around a single loop.
o Any break in the loop, such as a burn out or missing bulb, stops
the current from flowing.

parallel circuits- has two or more paths through which electric
charges may flow
o Each path leaves from the power source and returns to it.
o The current that flows through one path does not have to flow
through the other paths. (If one loop in the circuit is broken,
the current will still flow through the other loops.)
Directions: Circle the letter of the best answer.
1. A material through which an electric charge can easily move is a(n)
__________.
A. resistor
C. conductor
B. insulator
D. None of the above
2. An electric charge in motion is a(n) ___________.
A. electric current
C. insulator
B. conductor
D. None of the above
3. A material through which an electric charge moves slowly is a(n)
____________.
A. resistor
C. conductor
B. insulator
D. None of the above
Name: _____________________________ Date: _____________
Science Notes: Unit 3: Chapter 5
Electricity
Directions: Write the answers to the following questions in complete
sentences.
4. What is the difference between a parallel circuit and a series circuit?
A parallel circuit has two or more paths through which electric
charges can flow, so the current will still flow if one loop is broken. A
series circuit only allows electricity to flow in one circular path. If the
loop breaks, the current stops.
5. What does the plastic over the metal wires in a circuit do?
Plastic is an insulator that keeps electric current flowing through the
wires, and it also prevents people from receiving an electric shock when
handling the wires.
6. Explain the 4 parts of a circuit. Tell what each part does.
The energy source provides the energy to move electric charges.
Wires provide a path through which current can flow. Resistors
transform electrical energy into other forms of energy. The switch
opens and closes the circuit.
Lesson 2: How can energy change?


Energy is never lost, and it cannot be made or destroyed; however,
energy can transform, or change form.
o Electricity can change to light.
o Motion can change to sound.
o Wind can change to electricity.
Resistors use energy in a circuit by transforming electrical energy to
heat and light.
o The filament in a light bulb is its resistor.
o A filament is a thin, coiled wire that can get very hot without
melting. (See picture on page 160.)
o Some types of wires are good resistors.
Directions: Fill in the blanks.
1. A filament is a thin-coiled resistor that transforms electrical energy
into heat and light energy.
Name: _____________________________ Date: _____________
Science Notes: Unit 3: Chapter 5
Electricity
2. Friction is a force that acts when two surfaces rub together.
3. A resistor is an object that uses the energy in a circuit.
4. A violin transforms electrical energy into sound energy.
This statement is false because a violin transforms the energy of
motion into sound energy.
5. Charges exit a circuit with less energy than they had when entering
the circuit.
This statement is false because energy is never gained or lost. It is
only transformed.
6. Describe how electrical energy is transformed in a clothes dryer.
Resistors inside the dryer transform electrical energy into heat that
dries the clothes. The resistors also transform electrical energy into
energy of motion, which makes the drum spin, and sound energy.
**Test will consist of material from notes, textbook, and questions from
handouts completed in class.**