Unit 10 Review Sheet Answer Key
1. Atom
a. Define
An atom is the smallest unit of an element that
maintains the properties of that element.
b. Draw and Name the 3 parts of an atom and identify
their charges.
Proton – Positive
Neutron – Neutral
Electron - Negative
c. Give an example of a neutral atom
Same amount of protons as electrons (6 protons
and 6 electrons)
d. Give an example of an atom with a negative charge
4 protons and 9 electrons (more electrons than
protons)
2. Law of Electric Charges
a. Define
like charges repel, or push away and unlike
charges attract
Proton – Proton – Repel
Electron – Proton – Attract
3. Static electricity
a. Define
The electric charge at rest.
b. How is static electricity produced?
By friction or induction
c. Identify two examples of static electricity.
1. Lightning
2. Laundry sticking together in the dryer
3. Ms. Maier’s hair standing up when the
balloon was rubbed on it
4. Electric discharge
a. Give 2 examples and explain why they are examples
1. Lightning
2. Shocking someone
Both are quick releases of electrons from a
source.
5. Electric Charges
a. Name and describe three ways to charge an object.
1.
2.
3.
friction-rubbing
induction-when 2 objects are close to one
another which causes the atoms to rearrange
conduction-when two objects touch.
6. Electric Force
a. Define
The force (push/pull) between charged objects
b. What does electric force depend on?
-The amount of charge on each object
-The distance between the charges
7. Insulators
a. Give 3 examples and explain why they are examples.
Plastic, rubber, glass, wood, and air are good
insulators because they are materials in which
charges cannot move easily.
8. Conductors
a. Give an example and explain why it is an example
Most metals are good conductors, especially
copper, aluminum, and mercury because they are
materials in which charges can move through
easily.
Section 2 Notes-Electric Current and Electrical Energy
9. Electric Currents
a. Define
The rate at which charges pass a given point. The
higher the current is, the greater the number of
charges that pass the point each second.
b. Unit for measuring current
Amperes (amp)
c. Describe alternating current and give an example of
where it is used.
Alternating Current: the charges continually shift
from flowing in one direction to flowing in the
reverse. This is the current in your home.
d. Describe direct current and give an example of where it
is used.
Direct Current: the charges always flow in the
same direction. This is the current in batteries.
10. Measuring electricity
a. Describe voltage
It is the potential difference between two points
on a circuit. It is expressed in volts or V.
Voltage is a measure of how much work is
needed to move a charge between two points.
The higher the voltage is the more energy is
released per charge.
11. Resistance
a. Define
Resistance is the opposition to the flow of
electric charge. It is expressed in ohms.
b. What 3 factors does resistance depend on?
-width, length, temperature
-Good conductors have low resistance; poor conductors
have high resistance.
-The higher the temperature, the more resistance.
-A thick wire has less resistance than a thin wire.
-A short wire has less resistance than a long wire.
12. Circuits
a. Define
Closed path through which electric charges flow.
A switch is used to open and close a circuit.
b. Identify the three parts of a circuit.
Load: What you are turning on, such as a light
bulb or radio. They change electrical energy into
other forms, such as sound.
Electrical Current (Energy Pathway-Wires): What
the energy travels through.
Energy Source: Batteries, photocells,
thermocouple, or generator.
13. Series Circuit
a. What is a series circuit and where would you find one?
Series Circuit: There is only one path for the
charges to flow through. Used in decorative
lights (Christmas tree lights)
b. Draw a series circuit.
14. Parallel Circuits
a. What is a parallel circuit and where would you find one?
Parallel circuit: There is more than one path for
the energy to flow through. Used in homes.
b. Draw a parallel circuit.
15. Circuit Breakers and Fuses
a. How do circuit breakers and fuses keep our home safe?
-Fuses have thin strips of metal on them. If a
current is too high, the metal will melt, which will
stop the flow of electricity.
-Circuit Breakers: Circuit breakers are switches
that automatically open if the current is too high.
The open switch prevents any more electricity
from flowing.