Electricity Unit Review
1. Use the space below to draw two circuit diagrams. Each circuit should have a three-cell battery, and
three bulbs and a motor. In the first diagram, connect each bulb and the motor in series. In the second
diagram, connect each bulb and the motor in parallel.
2. Why is it important to consider power rating when shopping for a new appliance?
3. Describe the environmental impact of using coal as an energy resource.
4. How does a well-insulated oven, fridge, or house help to reduce pollution?
5. What is meant by the term sustainability?
6. Describe how digital transmission and storage of information has created both opportunities and
problems for society.
7. Compare the energy transformations in an oven and in a thermocouple. How are they similar? How
are they different?
8. List the four parts of an electric motor. What is the function of each part?
9. Describe one application of electrochemistry.
10. Consider the following three charged objects. Objects A and B are fixed in position, but object C is
free to move.
a)
Will object C move? Explain your answer.
b)
If you think object C will move, use an arrow to show its path of movement. Explain why you
think object C would take the path you have indicated.
11. Explain why you sometimes feel a shock when reaching for a doorknob after walking across carpet.
12. Describe the difference between current and static electricity.
13. Describe three ways you can protect yourself from electrical shock.
14. Name two sources of energy. Describe briefly how each can be used to make electricity.
15. In your own words, define the term conductor. What are the characteristics of a good conductor?
16. In your own words, define the term insulator. What are the characteristics of a good insulator?
17. Define AMPERAGE:
18. Define VOLTAGE:
19. What is the difference between a CELL and a BATTERY?
20. Explain the difference between a BREAKER and a FUSE:
21. What voltage is required to produce a current of 8.00 A with a resistance of 12.0 Ω?
22. What current will be produced in a circuit if wires are hooked up to a 12.0 V battery and a 15.0 Ω
resistor?
23. What is the resistance of a light bulb if a voltage of 120 V produces a current of 3.50 A?
24. A computer plugged into a 120 V outlet draws 3.0 A of current. How much power is the computer
using?
25. A laser can fire for 10 s with a power of up to 10 000 W. What is the energy this laser would use?
26. What is the efficiency of a device which uses 678 Joules of electrical energy to produce 400 Joules
of light energy?
27. How many kilowatt hours are used when a T.V. which has a power rating of 500 W is left on for
three days?
Answers:
1.
See page 312 for symbols. Se page 313 for sample series and parallel circuits.
2.
Low power rating will use electricity.
3.
Greenhouse gases are produced, as are other pollutants such as fly ash. See 351.
4.
Well insulated means less energy lost to surroundings. Less energy is used, which means less coal
or natural gas has to be burned to produce the electricity.
5.
See 353
6.
See 356 - 358.
7.
Oven: converts electrical energy into thermal energy. Thermocouple: converts thermal energy into
electrical energy. Opposite to each other.
8.
Armature: Coils where electricity produces electromagnets. Magnets: north - south repulsions
between armature and magnets causes the armature to spin. Brushes: allow the electricity to flow
into the commutator as it spins. Commutator: Allows electricity to flow into it, to the armature.
Commutator is split so electromagnet in armature changes polarity each half turn to allow the
armature to keep spinning.
9.
Any one of electrolysis, electroplating, anodizing or electrorefining. See 292-294.
10. C will move away from B (likes repel) and toward A (opposites attract). Path will be roughly arc
shaped away from B then back toward A.
11. Static charge builds up on you due to friction with the carpet. The static charge discharges into the
doorknob when you touch it.
12. Static: charge builds up, and may discharge. Current: a constant flow of electricity.
13. See 284 - 287.
14. See 345 - 348.
15. See 298 - 301
16. See 289 - 301
17. Amperage: how much electricity is flowing. See 305.
18. Voltage: how much energy the electricity has. See 305.
19. A cell uses chemical energy to produce electricity. A battery is two or more cells connected
together to produce electricity.
20. See 286.
21. 96 V
22. 0.8 A
23. 34.3 Ω
24. 360 W
25. 100,000 J or 100 kJ
26. 59%
27. 36 kW•h