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# [Science]: Electricity & Magnetism -- Electrical Power (Student Teacher's Notes)

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- 1. Open EndedWhat is the definition of power?
- 2. Open EndedWhat is the symbol for electrical power?
- 3. Open EndedWhat are the units for electrical power?
- 4. Open EndedWhat is the formula for electrical power? Label its components.
- 5. Open EndedHow can electric energy used by a device be determined by?
- 6. Open EndedWhat is the formula for electrical energy? Label its components.
- 7. Open EndedWhat does 1 kWh equal to?
- 8. Open Ended• A speaker system has a power rating of 200W and is used for 1800 seconds. How much energy is used?
- 9. Open Ended• A 4800 watt television is used for 5 hours. If the cost of electricity is $0.04 per kW*h, how much will it cost to run the television for 5 hours?
- 10. Open Ended• How much energy will an electrical appliance have consumed after 15 minutes' use if the current flowing through it has an intensity of 15 A and a Potential difference (V) of 120 V.
- 11. Open EndedWhat is potential difference?
- 12. Open EndedWhat is voltage?
- 13. Open EndedWhat causes electric shocks?
- 14. Open Ended1 W is equal to what?
- 15. Open EndedBooklet on Dynamic Electricity #8: Electrical energy can be measured in joules or in kilowatt hours. If 950 kWh of energy have been used, what is the consumption in joules?
- 16. Open EndedBooklet on Dynamic Electricity #9: How much will it cost to use a 1200-W microwave oven for 10 minutes if one kilowatt hour costs $0.067?
- 17. Open Ended[Txtbk pg. 173 #17]: How much energy will an electrical appliance have consumed after 15 minutes' use if the current flowing through it has an intensity of 15 A and the potential difference is 120 V?
- 18. Open EndedA hair dryer uses 0.6 kWh of electrical energy in 15 minutes. What is the electrical power of this dryer?
- 19. Open EndedHow would you convert 2.4 kWh to J?
- 20. Open EndedThe data sheets of two devices contain the following information: Device A: 120 V 15 A Device B: 220 V 5 A Which is the more powerful of the two devices?
- 21. Open EndedWhat is the electrical power of an engine that uses 3000 J of energy per hour?
- 22. Open EndedA 1000-W microwave oven operates for four minutes. What amount of work has it done?
- 23. Open Ended[From ST Review]: A student was asked to assemble a simple electrical circuit made of a resistor and a battery, an ammeter and a voltmeter. The diagram below represents the circuit that he assembled: (it is printed out) The ammeter reads is 0.80 A and the voltmeter reads 20 V. What is the electrical power of this circuit?
- 24. Open Ended[From ST Review]: What is the current drawn when a kettle with a power of 1.65 kW is connected to a 110V power supply?
- 25. Open EndedContinue this set with the questions in workbook.
- 26. Open Ended[From ST Review]: What is the voltage required by an electric grill with a power of 2.2 kW and current 20 A?
- 27. Open Ended[From ST Review]: In the electrical circuit represented below (it is printed out but the illustration is not important), the voltage is 100 V and resistor R has a value of 50 Ω. Calculate the electrical power of resistor R
- 28. Open Ended[From ST Review]: Explain the relationship between the power of an electrical appliance, the electrical energy it consumes and the amount of time it is in operation.
- 29. Open Ended[From ST Review]: 1. Which of the following would reduce the cost of using an electrical appliance? 1. Increase the operation time. 2. Use an appliance with a lower power rating. 3. Reduce the operation time. 4. Use an appliance with a higher power rating.
- 30. Open Ended[From ST Review]: Lynn wants to buy a new hair dryer. The store sells two different models. The rating plates of the two appliances are shown below: Model 1: 120 V 60 Hz 1200 W (1.2kW) Model 2: 120 V 60 Hz 1400 W (1.4kW) She usually dries her hair for about 15 minutes daily and she would like to use the least amount of energy possible. Which of the two models should Lynn buy? Explain your answer.
- 31. Open Ended[From ST Review]: Which equation would we use to calculate the electrical energy consumed, the power of an electrical appliance and the amount of time it is in operation?
- 32. Open Ended[From ST Review]: How much energy does an electric heater with a power of 200 W consume in 2.0 minutes?
- 33. Open Ended[From ST Review]: How much energy is consumed by an oven with an electrical power of 4000 W in use for 2.5 hours?
- 34. Open Ended[From ST Review]: How long does it take for a kettle with a power of 2000 W to use 30 000 J of energy?
- 35. Open Ended[From ST Review]: What is the power of an electric bulb that gives off 3600 J of energy in 10 minutes?
- 36. Open Ended[From ST Review]: A water heater has a resistor working with a potential difference of 220 V and a current of 50 A. Calculate the energy consumed by this water heater in 30 minutes. Show all your work.
- 37. Open EndedAn element in a circuit requires a potential difference of 120 V and offers a resistance of Ω. What is the intensity of the current flowing through the element?
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