Download Electricity Test Review

Electricity Test Review
1. Name 2 examples of insulators & 2 examples of conductors.
2. Name 3 ways to charge an object & give an example of one of them.
3. Name 3 ways to discharge an object & give an example of one of
them.
4. Should an operating floor be waxed? Using your knowledge of
electrostatics, explain why.
5. Explain how static & current electricity are similar, yet different.
6. Name the 4 components in a basic electric circuit. Name an example
of each in the circuits we built.
7. Draw the following schematic diagram symbols for the following:
a) bulb
e) resistor
b) cell
f) ground
c) battery (assume 2 cells in series)
g) motor
d) switch (1 that is open, 1 that is closed)
8. Draw a circuit diagram with the following info:
- a battery (assume 4 cells in series)
- 2 loads (1 resistor, 1 motor) so that if the motor overheats &
turns off, so does the resistor
- switch between the negative terminal of the cell & the 1st load
- a voltmeter that measures the potential difference of the 2nd load
9. Draw a circuit diagram with the following info:
- a battery (assume 2 cells in series)
- 2 loads (1 light, 1 resistor) so that if the light breaks, the resistor
continues to function
- switch that controls only the light bulb
- a ground for the entire circuit
10. Explain what an electrochemical cell is and how it works.
11. Explain how a cell is different from a battery.
12. Create a T-chart to compare & contrast primary vs. secondary cells.
Primary Cells
Secondary Cells
Similar
Different
13. Give an example of a device that uses:
a) primary cell(s)
b) secondary cell(s)
c) both
14. How is potential difference different from current?
15. How is current different from resistance?
16. What are the symbols we use to represent potential difference,
current, and resistance? What units do we use to measure them?
17. a) What is DC? What is AC?
b) How are they similar?
c) How are they different?
d) Name an example of an electrical load that functions on DC, and
one that works on AC.
18. If potential difference is increased (e.g., we add another cell) & we
keep resistance the same, what happens to current?
19. If resistance is increased (we add another load) & we keep potential
difference the same, what happens to current?
20. Calculate the potential difference in a circuit with a motor that uses
15 A of current and has a resistance of 8.0 ohms. *** R = V / I ***
21. Calculate the resistance of a dryer if it uses 240 V of energy and
current flows through it at a rate of 20.0 A.
22. How is measuring potential difference different from measuring
current when you have a circuit set up (e.g., where you place the
probes, what the dial on the multimeter is turned to, etc.)?
23. How much charge, in coulombs, flows through a 20 A outlet in 2
minutes?
*** I = Q / t ***
24. Which has more resistance: 3 loads in series or 3 loads in parallel?
Why?
25. How much electric power flows through a hair dryer that is turned
on for 5 minutes and uses 9300 J of energy?
*** P = E / t ***
26. Convert 5200 W to kW.
27. How much electrical energy is used by a fridge in 3.5 hours that has
a power rating of 5200 W? Your answer should be in kWh.
28. For how long, in hours, can you use your Wii if it uses and has a
power rating of 2.3 kW and uses 7.25 kWh of energy?
29. How efficient is a clothes washer that uses 54.5 kJ of energy to
produce 41 kJ of useful energy?
30. How efficient is a toaster oven used for 2.5 h if it uses 1.15 kW of
power, and produces 1.78 kWh of useful energy? Hint: Calculate
the total amount of energy used first, then calculate % efficiency.
31. How much would it cost you to use your toaster oven from the
question above for the 2.5 h if you used it at the most expensive
time of day, when electricity costs 10.8 cents / kWh? Hint: use the
amount of electrical energy used value you calculated to determine
your answer.
32. Complete the table below to describe the symbols & units of the
following electrical measurements. FYI, both time & energy can
have 2 different units, depending on the equation you’re using.
I is the symbol for …….., measured in ……….., …..
I=Q/t
Q is the symbol for …….., measured in ……….., …..
t is the symbol for …….., measured in ……….., …..
33.
34.
35.
36.
37.
38.
39.
R=V/I
R is the symbol for …….., measured in ……….., …..
V is the symbol for …….., measured in ……….., …..
I is the symbol for …….., measured in ……….., …..
P=E/t
P is the symbol for …….., measured in ……….., …..
E is the symbol for …….., measured in ……….., …..
t is the symbol for …….., measured in ……….., …..
P is the symbol for …….., measured in ……….., …..
Eused = P  t E is the symbol for …….., measured in ……….., …..
t is the symbol for …….., measured in ……….., …..
Name 4 things that you learned about in class that your parents can
do to save $$ on their next electricity bill.
What are 4 safety devices that can be used to prevent excess current
from flowing through circuits in your home?
Explain how one of the safety devices from above functions to break
the flow of electrons in a circuit.
Name 4 “do”s and/or “don’t”s of electrical safety in your house or
outdoors.
Explain how electrical energy is generated at a generating station.
You can choose the energy source.
a) Name 2 examples of renewable energy sources, and 2 nonrenewable.
b) What are 2 advantages to using renewable energy?
c) What are 2 disadvantages?
Explain how the electricity gets from the generating station to your
house.
Answers to Word Problems
20. 120 V
21. 12.0 
23. 240 C
25. 31 W
26. 5.2 kW
27. 18.2 kWh
28. 3.15 h
29. 75%
30. 62%
31. 31.05 ¢
32.
I=Q/t
I is current, measured in amperes, A
Q is charge, measured in coulombs, C
t is time, measured in seconds, s
R=V/I
R is resistance, measured in ohms, 
V is potential difference, measured in volts, V
I is current, measured in amperes, A
P=E/t
P is power, measured in watts, W
E is energy, measured in joules, J
t is time, measured in seconds, s
Eused = P  t
P is power, measured in kilowatts, kW
E is energy measured in kilowatts hours, kWh
t is time, measured in hours, h