Electricity and Magnetism
Test Review
DEFINE

These are in the book, go for it.

What is Ohm's Law?
The relationship between current, resistance and voltage within a circuit.

What does each variable stand for and what are the units?
I= Current (Amps), V= Voltage (v), R= Resistance (Ω)

Write the triangle for Ohm's Law

Give the 3 versions of Ohm's Law (Equation when solving for voltage?
current? resistance?)
I=V/R
V=IR
R=V/I

According to Ohm's law, which would require the greater voltage to
move the current; 10 ohms resistance or 20 ohms resistance? Why?
The 20 Ω resistor would require more voltage to overcome the resistance

List the differences between series and parallel circuits (Refer to your
T-chart)
Series
Parallel
Draw a Picture
Draw a picture
Remove a light bulb, the rest go
out
Remove a light bulb, the
remaining bulbs stay lit
Total resistance is added together
Resistance is not added together
Current stays the same
Voltage is the same, current is
different through each branch
depending on the resistance
Ex: Christmas lights
Ex: Household lights

What type of electricity does not require a wire? Give 2 examples of
this type of electricity.
Static electricity. Examples are lightning, rubbing feet against carpet

Which subatomic particles move within the wire?
Electrons

What is the standard voltage in a home?
120 V

What is alternating current?
Current that changes direction over a set period of time.
Commonly multiple times a second.

What is direct current?
Current that flows only in one direction. It is DIRECT.

Give 3 examples of things that use AC
Washing machine, refrigerator, microwave

Give 3 examples of things that use DC.
Anything that has an internal battery such as phones, tvs, flashlights.
What is an AC/DC adapter?
Converts alternating current (which is the current inside your walls) into direct
current to be used by something with a battery such as when you plug your
phone into the wall.
 What direction does current flow?

Current flows from high to low.

What is the difference between a wet cell battery and a dry cell
battery? Give an example of each.
A dry cell battery has an electrolyte paste that electrons can flow through. These
Are small batteries like AA and AAA. A wet cell battery has a liquid electrolyte that
The electrons flow through. These are bigger batteries like car batteries.

What is the equation for Power?
P= IV so Power= Current x Voltage

What is the equation for Electrical Energy?
E=Pt so Energy = Power x time

Name 3 good conductors.

Copper, steel, brass, cast iron

Name 3 good insulators.
Styrofoam, wood and rubber

What makes a material a good conductor?
Good conductors allow electrons to move freely, so electricity flows
through these objects.

What makes a material a good insulator?
An insulator does not allow electrons to flow freely.

If two materials of opposite charge are brought together
what happens?
If 2 opposite charges are placed together, they will attract.
If 2 of the same charges are placed together, they will repel.
DEFINE

These are also in the book, go for it.

Name 3 magnetic materials and 3 nonmagnetic materials.
Magnetic materials = Iron, Nickel and steel
Non magnetic materials = Plastic, stainless steel, and paper

What are the two ends of a magnet called?
Poles. There is a North pole and a South pole.

What happens when a magnet is broken in half?
There are 2 separate magnets created. Both have a North AND South pole

What small shavings are typically used to show magnetic fields?
Iron filings

The South pole of a magnet should be attracted to which end of
Earth?
The North pole because opposites attract

What is an electromagnet?
A type of magnet in which magnetic field is produced by an electric current


What 2 things will control how strongly two magnets are attracted or
repelled?
Strength of the individual magnets and distance between the magnets
What is a galvanometer?
An instrument that detects electric current.

If a circuit has a voltage of 45 V and a current of 5.0 A, what is the
resistance?
R=V/I
R= 45V/5A
R= 9 Ω

In this circuit, there is a resistance of 40 Ω and a current of 0.15 A,
what is the voltage?
V = IR
V = .15A x 40Ω
V=6v

If a circuit has a voltage of 500 V and a resistance of 250 Ω, what is
the current?
I = V/R
I = 500v/250Ω
I = 2A

If a circuit has a voltage of 400 V and a resistance of 80 Ω, what is
the current?
I = V/R
I = 400v/80Ω
I = 5A

In a circuit, there is a resistance of 400 Ω and a current of 0.01 A,
what is the voltage?
V = IR
V = .01A x 400Ω
V=4v

If a small appliance is rated at a current of 10 amps and a voltage of
120 volts, what is the power rating?
P = IV
P = 10 A x 120 v
P = 1200 watts OR 1.2 kilowatts

If a blender is plugged into a 110 V outlet that supplies 2.7 A of
current, what amount of power is used by the blender?
P = IV
P = 2.7 A x 110 v
P = 297 watts OR .297 kilowatts

a.
A motor is connected to a 12-V battery with a current of 1.5 A
How much power is delivered to the motor?
P = IV
P = 1.5 A x 12 v
P = 18 watts OR .018 kilowatts
b. How much energy is transformed if the motor runs for 15 min?
E = Pt
E = .018 kW x .25 hr
E = .0045 kWhr