ELECTRICITY UNIT REVIEW

Transcription

1 ELECTRICITY UNIT REVIEW S1-3-04: How does the Atomic Model help to explain static electricity? 1. Which best describes static electricity? a) charges that can be collected and held in one place b) charges that exist on a neutral object c) charges that power your computer d) charges that travel through a conductor 2. Which statements describes a solid neutral object becoming positively charged? a) Electrons have been added to this object. b) Electrons have been removed from this object. c) Protons have been added to this object. d) Protons have been removed from this object. 3. An object contains 5 million electrons. It is neutral. How can this be? a) Electrons have no charge. b) It also contains 5 million protons. c) The electrons are spread out evenly in the object. d) The object is an insulator. 4. Which is true of charged objects? a) Like charges attract and neutral objects are attracted to charged objects. b) Like charges attract and opposite charges repel. c) Like charges repel and opposite charges attract. d) Like charges repel and neutral objects are repelled by charged objects. 5. The diagram below represents a neutral solid object. Use ( ) to represent electrons and (+) to represent protons to complete the diagrams. a) A second, positively charged rod is brought close to the original object. b) The positively charged rod touches the original object.

2 S1-3-11: What is electricity and how is it created? 6. List one example of how static and current electricity are similar, and list one difference. 7. Which is not a common energy source used to produce electrical energy? a) elastic bands b) generators c) piezoelectric crystals d) thermocouples 8. In a chemical cell, electrons move from: a) The negative electrode to the positive electrode. b) The positive electrode to the negative electrode. c) The positive electrode to the positive electrode. d) The negative electrode to the negative electrode. S1-3-12: What do current, voltage and resistance mean for electrons? 9. Which combination of materials could be used to produce the best electrochemical cell? a) an aluminum electrode, a copper electrode, and an acidic solution b) an aluminum electrode, a copper electrode, and water c) two silver electrodes and an acidic solution d) two silver electrodes and water 10. What is the name of an electric device that slows down current and changes electrical energy into other forms? a) Battery b) Conductor c) Resistor d) switch 11. Which correctly describes a load in an electric circuit? a) It can turn the circuit on or off by closing or opening the circuit. b) It is the source of electric energy. c) It is the wire through which electric current flows. d) It transforms electrical energy into useful forms of energy. 12. Describe a generator and explain why it is important in Manitoba?

3 13. Using a simple formula if needed, explain the meaning of voltage. 14. Using a simple formula if needed, explain the meaning of current S1-3-13: What is a schematic and how are they used as information for a circuit? 1. Draw the schematic symbol in the right hand a) bulb b) battery c) open switch d) ammeter

4 2. Draw a circuit diagram of a parallel circuit consisting of a single 9.0 V electrical source, an open switch controlling the electron flow in the entire circuit, and three 5.0 ohms resistors. Show the direction of electrons. 3. Draw a schematic diagram for a series circuit made up of 2 cells in series with a switch and 3 lamps. 4. Draw the schematic of this circuit representation next to it: S1-3-17: What are the similarities and differences between series and parallel circuits? 5. How is current effected by the resistance of a circuit in series versus parallel circuits? 6. A battery is connected to two light bulbs connected in parallel. If the first light bulb burns out, what happens to the second light bulb? Explain.

5 7. A student measures the voltage of identical cells to be 6.0 V each. Indicate the circuit voltage if a. Two of these cells (at 6.0 V each) were connected in parallel b. Four of these cells were connected in series 8. Calculate the missing source voltage (V s ) in the following circuit diagram. V S = 9. Circle the best term in the brackets to correctly complete each statement. a) A parallel circuit has (only one / more than one) path for current to travel. b) Two different resistors are connected in parallel. The current through one of the resistors will be (equal to / different from) the current through the other resistor. c) If two different resistors are connected in parallel, the voltage across one resistor will be (equal to / different from) the voltage across the second resistor. d) By adding a resistor in parallel with an original resistor, the total resistance of the circuit (increases / decreases). e) The total current entering the junction of a parallel circuit must be (equal to / different from) the sum of the currents through each branch of the parallel circuit. 10. Fill in the Following Table Letter Variable (word) Unit of Measurement (word) I Q E P V t R

6 11. In the circuit below, what are the readings on the voltmeter V, and ammeter A? Voltmeter, V Ammeter, A a) 8.0 V 1.0 A b) 4.0 V 3.0 A c) 8.0 V 3.0 A d) 12 V 9.0 A 12. In the circuit below, what are the readings on the voltmeter V, and ammeter A? Voltmeter, V Ammeter, A a) 9.0 V 2.0 A b) 9.0 V 5.0 A c) 12 V 5.0 A d) 12 V 12 A 13. Two identical resistors are connected in series to a battery. How does the current through the second resistor compare to the current through the first resistor? a. Half the current b. No current c. The same current d. Twice the current 14. A load is connected to a battery. If a second identical load is added in parallel to the first, what happens to the total resistance of the circuit and the current leaving the battery? a. Total resistance decreases and the current decreases. b. Total resistance decreases and the current increases. c. Total resistance increases and the current decreases. d. Total resistance increases and the current increases. S1 3 18: How is a household wired to ensure safety? 15. Explain the advantage of having a household wired in parallel. 16. Explain the need for circuit breakers.

7 S1 3 20: What is electrical power and how does it vary in appliances? 17. Which units would be used if measuring a large amount of energy? a. Coulomb b. Joule c. kilowatt hour d. watt 18. What is the current through a 180 W light bulb, if it is connected to 120v? a) 0.67 A b) 1.5 A c) 120 A d) S1 3 22: How can you lower electrical energy use of a household? 19. A 1400 W hair dryer is used for 15 min. (a) Calculate the electrical energy consumed in the following units. (i) joules (ii) kilowatt hours (b) If the cost of electricity is $0.08 per kwh, calculate how much it cost to use the hair dryer. 20. The hydro meter below was read at the beginning of three different months (May - A, June - B) for a Winnipeg sales business. Write the reading for each month in the blanks provided May Bill: June Bill: July Bill: a) How many kwh was consumed in the month of June? b) Calculate the amount owing for each month, in dollars, if the cost per kwh is 6.8 cents.

8 21. Use the Energuide sticker below to answer the questions. How much energy would you expect to use in a year with this appliance? Compared to similar models, would you consider this model to be efficient choice? If the electricity you used cost $0.07 per kwh, what is the average cost per month when using the appliance? 22. Match the term on the left with the best descriptor on the right. Each descriptor may be used only once. Term junction series circuit parallel circuit joule watt insulator conductor efficiency ohm current ammeter voltmeter ampere load switch coulomb circuit power A. more than one path for current to travel B. location where a circuit splits or reconnects C. device used in homes to protect against overload D. can open or close a circuit E. the unit of resistance F. a material the holds electric charge in place G. metal is an example of this H. charge that remains in one location I. a unit of power measurement J. amount of electrical potential energy in a circuit K. a measure of energy use over time L. unit of charge (group of electrons) N. a unit of energy measurement O. the unit of current P. a circuit where each thing is one after another Q. the flow of electrons through a conductor R. a resistor that converts energy into useful work S. a meter used to measure current T. a complete path for current to travel U. a device used to measure electrical potential comparison of energy used or wasted to energy input