Study Guide for Electricity Test 2014
Name:__________________________________________________________ per._____
Be able to explain the following concepts/vocabulary words:
A. Resistance- opposes flow of electrons (slows the circuit)
B. Battery- supplies voltage in a circuit because of a chemical reaction inside creating a build
up of charge and difference in potential energy.
C. Voltage- potential (energy) difference. It is the “force” that will power the circuit.
D. Amps- unit for measuring current
E. Ohms-unit for measuring resistance
F. Volts-unit for measuring voltage
G. Electron-negatively charged subatomic particles that flow through a circuit to make
electricity
H. Multimeter-a device used to measure current, resistance and voltage in a circuit.
I. Light bulb- an example of a resistor in a circuit
J. Current- measure of the electrons moving through a circuit (how many pass a point in one
second)
K. Series- a circuit in with only ONE pathway for electrons to flow through
L. Parallel- a circuit in with MORE than one pathway for electrons to flow through
M. Conductors- any material that allows electrons to easily pass through
N. Insulators- any material that does not allow electrons to easily pass through
O. Closed Circuit- will allow electrons to flow through it because the pathway is complete
(no breaks)
P. Open Circuit -will NOT allow electrons to flow through it because the pathway is NOT
complete (breaks in it- like an open switch)
Review Questions:
1. What is actually flowing through a circuit creating a current? _______electrons______
2. What is voltage? How does changing voltage affect a current?
 Voltage is the FORCE created when there is a difference in potential energy
between two points. (We compared it the the water pressure behind a faucet due to
the difference in water pressure when you open a tap. Just like with water, electrons
will flow from where this is more PE to where there is less PE)
 Increasing voltage increases current, decreasing it decreases current
3. List three devices that can be a resistor in a circuit.
Light bulb, fan, variable resistors like a light dimmer… (Anything that slows down
current)
4. How do resistors affect current?
They reduce it. When resistance is increased, you will see a reduction in the current.
5. The direction of electrical current in a circuit is away from the ____negative____ end of the
battery and toward the ___positive_______ end.
6. How does potential energy difference determine which direction electrons will flow?
Electrons always flow from HIGH potential energy toward LOW potential energy.
7. Write what the following units measure: (ex. Grams- Mass)
a. Amperes- ___Current___________
b. Volts- _____Voltage (potential energy difference)______
c. Coulombs- ___charge___________
d. Ohms- _____resistance___________
e. Joules- ____energy___________
8. Draw an open circuit with a wire, battery, light bulb and switch below. Would the light bulb
light? Why?
No, the light bulb will not light because the circuit is not complete
and therefore the electrons will not be able to flow.
9. How could you make it light? Why would that work?
Close the switch to complete the circuit and allow electrons to flow through the light bulb.
10. Draw a series circuit below with two light bulbs.
11. Draw a parallel circuit below with two light bulbs.
type of circuit?
What is the advantage to making this
you can turn one light off without turning off the other
because there are TWO paths for electrons to take.
12. What are ways you can INCREASE current in a circuit?
Increase voltage (add a battery) , decrease resistance
13. What are ways you can DECREASE current in a circuit?
Decrease voltage, increase resistance (add a light bulb)
14. Review the energy conversions we discussed in class. (for example- describe the energy
transfers that take place when you open a “hot hands” warmer and place it in your hands)
a. The example of hot hands…. Chemical Thermal
Application Questions:
15. The greater the resistance in a circuit, the less the____current______________.
16. Explain how a battery in a circuit is similar to a water pump.
The battery provides the voltage. Voltage is the FORCE created when there is a difference
in potential energy between two points. (We compared it to the water pressure behind a
faucet due to the difference in water pressure when you open a tap. Just like with water,
electrons will flow from where this is more PE to where there is less PE)
17. A circuit contains one light bulb and a battery. What happens to the total resistance in the
circuit if you replace the one light bulb with a string of four identical bulbs? Why?
Resistance increases because you have added more resistors. (Resistors by definition
reduce current so current would decrease)
18. The current in a circuit increases if the __voltage____ increases and decreases if the
___voltage___________ decreases.
19. A battery is connected to a light bulb, creating a simple circuit. Explain what will happen to
the current in the circuit if:
a. The bulb is replaced with a bulb having a higher resistance.
The current will decrease
b. The bulb is replaced with a bulb having lower resistance.
The current will increase.
c. The battery is replaced with a battery having a greater voltage.
The current will increase.
20. Why is it important to always have dry hands when working with electric currents?
Because water is a conductor and will allow electrons to flow through it into your hand.
21. What voltage would the electrical meter show in each of the diagrams below?
Circuit a will read 1.5 volts. Circuit B will not read any volts. Both circuits have 1.5 volts, but the
multimeter will only read that for set up A. You must connect to both terminals to get the
potential energy difference between them (which IS voltage)
22. Which of the following diagrams shows the correct way to measure current in a circuit?
Only B. This set up allows the electrons to run THROUGH the multimeter. It is IN THE
SERIES.
23. Which of the following circuits would light a light bulb the brightest? Why?
9V
9V
3V
Circuit A will have the brightest bulb because it has the highest current running through it. The
other two either have less volts or more resistance.