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# Power and Resistance

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### Power and Resistance

1. 1. RESISTANCE
2. 2. QUESTIONS TO ANSWER How can the resistance of an ohmic conductor be described? What about non-ohmic conductors? What is an ohm literally a measure of? (ie. something per something) What is Ohm’s law and does it apply to both ohmic and non-ohmic conductors?
3. 3. QUESTIONS TO ANSWER Wires are designed to offer as little resistance as practially possible. Find out how the following characteristics of a wire affects its resistance: Length Diameter The type of metal used (eg. compare copper and silver) What is the equation that describes the relationship between these three factors? Design a more efﬁcient wire.
4. 4. If normal household copper wiring is 1.8mm in diameter, use the formula from the previous question to ﬁnd out the resistance of a 10m long piece. Then ﬁnd out what voltage drop you would get if a current of 10A ﬂowed through it. Compare the voltage drop of the normal household wiring from above with a 10m length of your new and improved wiring. How much more efﬁcient is your wiring? Would it be worth the extra cost?
5. 5. ENERGY AND POWER
6. 6. CALCULATING ENERGY AND POWER What is the formula for calculating electrical energy? What is the unit it is measured in? What is the formula for calculating electrical power? What is the unit it is measured in? Convert joules into the more well-known unit for measuring power: kilowatt hour (kWh). How many joules are in 1kWh? How much does your household pay per kWh (refer to an electricity bill).