Static Electricity Ch 11, 12, 13 PDF

# TEST REVIEW ## STATIC ELECTRICITY (11) **NOTE: STATIC ELECTRICITY** 1. Explain two ways in which an atom can become an ion: The atom has to be charged to become an ion. 2. What can sometimes happen when two neutral objects come in contact with each other? When two neutral objects come in cont...

# TEST REVIEW ## STATIC ELECTRICITY (11) **NOTE: STATIC ELECTRICITY** 1. Explain two ways in which an atom can become an ion: The atom has to be charged to become an ion. 2. What can sometimes happen when two neutral objects come in contact with each other? When two neutral objects come in contact, electrons get transferred. 3. Describe the basic structure of the atom. Proton, electron, neutron. 4. What is static electricity? Is the imbalance of electric charge on the surface of an object. 5. Why can electroscopes be useful? To detect electric charges. 6. How do electroscopes show that electric charges are present? **NOTE: LAW OF ELECTRIC CHARGES** 7. State the Law of Electric Charges Positive and negative attract Neg and neg is repel pos and pos repel 8. Explain how charged objects can become attracted to neutral objects (explain the concept of induced charge separation). **NOTE: ELECTROSCOPES** 9. Explain how a metal leaf electroscope works. 10. Explain how electrostatic paint sprayers, dusters and precipitators work. Sprayers: Dusters: Precipitators: **NOTE: CHARGING OBJECTS** 11. List the three ways to charge an object: 1. Friction 2. Contact (conduction) 3. Induction 12. What is the electrostatic series chart useful for? 13. Explain how charging by friction works. This occurs when two different neutral materials are rubbed together or touch and electric charges are transferred from one object to another. 14. Why is static cling worse in winter? In the winter, the air is more dry so static electricity problems get worse because moisture in the air normally helps to conduct away excess charge. **NOTE: CHARGING OBJECTS** 15. Explain how charging by contact works Two objects with different amounts of electric charge come in contact and electrons move from one object to the other. 16. What is grounding? Grounding is a process in which objects can lose their electric charge. If a charged object is attached to the ground with a conductor, it losses the electric charge into the ground. **NOTE: CONDUCTORS and INSULATOR’S** 17. What is the difference between a conductor and an insulator. Give an example for each. **h** 6. A large tube in a television set has a resistance of 50000 ohms and draws a current of 0.160 amps. What is the potential difference across the tube? 7. An electric toaster has a resistance of 12 Ω. What current will it draw from the 120 V supply? 8. What potential difference is required to produce a current of 8.0 A in a load having a resistance of 64 ohms? 9. A voltmeter connected across the ends of a heating coil indicates a potential difference of 60 V when an ammeter shows a current through the coil of 3.0 A. What is the resistance of the coil? 10. A flashlight bulb has a resistance of 7.5 ohms and is connected to a dry cell will a potential difference of 3.0 V. What is the current through the bulb? 11. What is the potential difference across a motor with a resistance of 40 Ω if the motor draws a current of 6.0 A? **i** # ELECTRICITY CHAPTER 12 ## Questions ## **12.1 - Current Electricity** 1. What is the difference between current electricity and static electricity? 2. What is the difference between alternating current (AC) and direct current (DC)? 3. Explain why conductors and insulators are both required to construct the electrical wiring in your home. 4. What is required for electricity to flow? Explain. ## **12.2 - Electric Circuits** 1. Name the four parts of an electric circuit. 2. What is the difference between an open circuit and closed circuit? 3. In your own words, describe an electrical circuit. 4. A student builds a circuit that has a source of electrical energy, connecting wires, a switch, and a load (in this case, a light bulb). However, the circuit doesn't work. Suggest three possible reasons why the circuit does not work. ## **12.3 - Electrical Energy** 1. In your opinion, what are the three most important uses of electrical energy? 2. What type of electric cell would be best used in a flashlight and a smoke detector? Explain. 3. What is the difference between a cell and a battery? 4. What is the difference between a primary cell and secondary cell? 5. In space, fuel cells are used to supply power to where it's needed. Why do they use fuel cells for this purpose? ## **12.5 - Generating Electricity** 1. Explain three disadvantages associated with burning fossil fuels to generate electricity. 2. Explain why renewable resources are becoming more popular (as opposed to non-renewable ones). 3. Why do we still use non-renewable resources to generate electrical energy? 4. Explain how electricity is produced using water. 5. Explain how electricity is produced in a nuclear power plant. 6. What is a "photovoltaic cell"? 7. Name one disadvantage for using renewable energy to generate electricity. **NOTE: CHARGING BY INDUCTION** 18. Explain how to charge an object temporarily by induction. 19. Explain in detail how to charge an object permanently and positive after being charged by induction. Draw diagrams if you wish in your explanation. Include step-by-step statements. **NOTE: ELECTRIC DISCHARGE** 20. What does "electric discharge" mean? 21. Give an example of electric discharge. 22. What is lightning? 23. Why are lightning rods useful? **j** ## **12.7 – Electrical Power and Efficiency** 1. Identify three ways that you can conserve electrical energy. 2. Explain how Energuide labels are useful to consumers. 3. When purchasing an electrical device, what are the two financial costs you need to consider? Are there any environmental considerations you would make? Explain your reasoning. 4. Calculate the efficiency of a compact fluorescent light bulb if it produces 30 J of light-energy, while using 95 J of electrical energy. $30 \div 95 = 31.6%$ 5. Calculate the cost of operating the following devices. The cost of electricity is 12¢/kWh $Cost = 0.12 \times Power (kW) \times Time (hours)$ . * a) a 100 W incandescent light bulb for 1000 hours. * b) A 400 W computer for 5 hours a day, for an entire month (30 days). * c) a refrigerator operating at its peak power of 750 W for one year. **K: 14 T/I: 6/A:6** # SCIENCE TEST ## Electricity Ch. 12 **NAME: Eva Norville** 1. What are the two main forms of current electricity? Explain how they differ from each other. * **DC** * **AC** 2. What are the four components (parts) of an electric circuit? 1. **Power Source** 2. **Wires** 3. **Load (device)** 4. **Switch** 3. What is the difference between: *K: 2+2+2= 6 marks* * a) an open circuit and a closed circuit? * **Open Circuit:** path is interrupted, so electricity can't flow. * **Closed Circuit:** path is not interrupted, electricity flows. * b) a primary cell and a secondary cell? * **Primary Cell:** can only be used once. * **Secondary Cell:** can be recharged. * c) static electricity and current electricity? * **Static Electricity:** electric charge builds up on a surface and stays there, then suddenly releases the charge. * **Current Electricity:** electrons flow through a wire. It's a continuous flow of charge. 4. Why do some people operate large appliances (such as the washing machine and dryer) only during certain times of the day? *K: 1 mark* Because it's cheaper and saves energy. **e** # THINKING/INQUIRY SECTION 5. Give an example of an electrical load. Justify your answer. *T/1: 2 marks* A light bulb. Takes energy from the source (see #2) and turns it into electrical energy (light and heat). 6. Calculate the efficiency of a compact fluorescent light bulb it if produces 30 J of light energy, while using 95 J of electrical energy. *T/1: 2 marks* $$ \frac{Light\ Energy}{Electrical\ Energy} \times 100 = \frac{30\ J}{95\ J} \times 100 = 31.6\% $$ 7. A 7W LED light bulb is left on 24 hours per day for 1 year. Electricity costs 6.5 cents per kilowatt-hour. Calculate the cost to operate the light bulb. *T/1: 2 marks* $$ Cost = Power (kW) \times Time (hours) \times Cost\ per\ kWh = 0.007kW \times 8760 (24/hr\times365\ days) \times 0.65/kWh = $39.85 $$ # APPLICATION SECTION 8. Fuel cells were used on the space shuttle to provide the shuttle with all of its electrical energy. Explain why. *A: 2 marks* 9. Describe the process, in detail, of any way of generating electricity: * a) that uses a renewable resource: *A: 2 marks* * b) that uses a non-renewable resource: *A: 2 marks* **f** # ELECTRICITY QUESTIONS ## SNC 1D1 ## Chapter 13 **NOTE: CIRCUITS and CIRCUIT DIAGRAMS** 1. What is the difference between a battery and a cell? 2. a) What is the difference between a series and a parallel circuit? b) What type of circuit is most commonly found in your house? **NOTE: ELECTRIC CURRENT** 3. What does electric current mean? 4. What does an ammeter do? 5. What is the point of having circuit breakers or fuses in your home? 6. How do you hook up an ammeter properly... series or in parallel? 7. a) What is the unit for current? b) What is the symbol for current? 8. Why can electrical shocks be dangerous (not just that "it can kill you"!) 9. What is meant by the "let go threshold"? **Review Part** **g** # WORKSHEET ## OHM's Law **NAME:** **USE THESE FORMULAS to solve the following questions. Show all work.** $$ V=volts\\ I=amps\\ R = ohms\\ V=IR\\ I=V \div R\\ R=V \div I $$ 1. Find the resistance of an electric light bulb if there is a current of 0.80 A when the voltage (potential difference) across the bulb is 120 V. 2. What is the potential difference (voltage) across a toaster of resistance 13.7 ohms when the current through it is 8.75 A? $$ V = IR = (8.75) (13.7) = 119.875 = 120\ V $$ 3. What is the current through an electric baseboard heater with a resistance of 38 ohms when the potential difference across it is 240 V? $$ I = V \div R = 240 \div 38 = 6.315 = 6.3 $$ 4. A portable radio is connected to a 9.0 V battery and draws a current of 0.025 A. What is the resistance of the radio? $$ R = V \div I = 9.0 \div 0.025 = 360\ \Omega $$ 5. An electric clothes dryer is connected to a 230 V source of electric potential. If it has a resistance of 9.2 ohms (Ω), calculate the current it draws. $$ R = V \div I = 230 \div 9.2 = 25 $$