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GCSE Science A Physics 1 Transmission of ElectricityEnergy Supply Learning Outcomes Distinguish between Power and Energy. And use the equation Energy = Power x Time Use the equations: Units Used (kWh) = Power (kW) x Time (h) Cost (p) = Units used x Cost per unit (p) Use data to make comparisons of different sources of domestic energy. Distinguish between Power and Energy. And use the equation Energy = Power x Time Use the equations: Units Used (kWh) = Power (kW) x Time (h) Cost (p) = Units used x Cost per unit (p) Use data to make comparisons of different sources of domestic energy.

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GCSE Science A Physics 1 Transmission of ElectricityEnergy Supply Key Words: Power: The rate of flow of energy Energy: The ability to do work Power: The rate of flow of energy Energy: The ability to do work

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GCSE Science A Physics 1 Transmission of Electricity Water heater25% Fridge/ freezer 15% Bulbs 25% Oven 5% Tumble dryer3.5% Television 2.5% Dish washer1.5% Washing machine <1% Computer <1% Others 2% Drag the appropriate labels to the correct boxes in order to complete the graph showing the percentage use of electricity in the home.

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GCSE Science A Physics 1 Transmission of ElectricityEnergy Supply EnergyPower DefinitionEnergy is the ability to change your environment. In order to heat something up, make something move, glow, or stretch etc. you need energy! Power is the rate of flow of energy. To make something move faster, glow brighter etc. Requires more power. Power is the energy per second UnitJouleJoule/Second (Watt)

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GCSE Science A Physics 1 Transmission of ElectricityEnergy Supply Now rearrange this equation using an equation triangle!

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GCSE Science A Physics 1 Transmission of Electricity The power rating of a bulb is 60W. This means that 60 Joules of electrical energy is used every second to produce light and heat energy. The power rating of a kettle is 2kW. This means that 2000 Joules of electrical energy is used every second to produce heat energy and to boil the water. Remember that there are1000W for every 1kW. So, 2kW = 2000W = 2000J/s 0.1kW = 100W = 100J/s 3.7kW = 3700W = 3700J/s 0.02kW = 20W = 20J/s Remember that there are1000W for every 1kW. So, 2kW = 2000W = 2000J/s 0.1kW = 100W = 100J/s 3.7kW = 3700W = 3700J/s 0.02kW = 20W = 20J/s The unit of power is the Watt (W), and 1W is equivalent to 1J of energy per second.

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GCSE Science A Physics 1 Transmission of Electricity You will need to be able to use: Power (W) = voltage (v) current (A) You will need to be able to use: Power (W) = voltage (v) current (A) Electrical power is the measure of how fast electrical energy can be transformed into other energies. Power (W) = current (A) voltage (V) = = 1008W ( about 1kW ) Power(W) = current (A) voltage (V) = = 96W The current flowing through a toaster is 4.2A, The mains voltage is 240V. What is the power of the toaster? If the mains voltage is 240V, what is the power of a sound system, if there is 0.4A of current flowing through it? Answer

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GCSE Science A Physics 1 Transmission of Electricity This small power station is producing 250kW of electricity. This step-up transformer is increasing the voltage to 25,000V. What will the current be through the cables? Step-up- transformer Answer Power (W) = current (A) voltage (V) 250,000 = current 25, ,000 = current = 10A 25,000

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GCSE Science A Physics 1 Transmission of Electricity I pay my electricity bill every month by direct debit I pay my electricity bill every quarter How much energy do we use?

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GCSE Science A Physics 1 Transmission of Electricity 100W Power Power is the rate of doing work, or the rate of energy transfer and is measured in Watts. There are 1000W in every 1kW

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GCSE Science A Physics 1 Transmission of Electricity Highest value Lowest value 100W 0.4kW 30W 20kW 650W 1kW 0.05kW Click here for the answer Click here for the answer

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GCSE Science A Physics 1 Transmission of Electricity Highest value Lowest value 100W 0.4kW 30W 20kW 650W 1kW 0.05kW 20,000W 1,000W 650W 400W 100W 50W 30W

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GCSE Science A Physics 1 Transmission of Electricity energy transfer = power time There are 1000W in every 1kW So, a 100W light bulb will transfer 100J of electrical energy into a total of 100J of light and heat energy per second. In fact, 1W = 1J/s In fact, 1W = 1J/s And a 2kW kettle will transfer 2,000J of electrical energy into a total of 2,000J of heat energy per second.

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GCSE Science A Physics 1 Transmission of Electricity Units used (kWh) = power (kW) time (h) kWh 391M This was the type of electric meter that would have measured the amount of electricity used in your home. It measured the electrical energy used in units of 1kWh (equivalent to a 1000W device running for 1 hour). You are then billed on the number of units used in total for a given period.

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GCSE Science A Physics 1 Transmission of Electricity Units of Energy used (kWh) = power (kW) time (h) These days, digital electric meters are the norm. But although it looks different, the amount of electricity used is still measured in kWh kWh Cost(£/p) = units used(kWh) cost per unit(£/p)

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GCSE Science A Physics 1 Transmission of Electricity Below are the meter readings taken at particular times during the year for a 3 bedroom house kWh 2207 kWh 3519 kWh September 9 th (2011) January 9 th (2012) May 9 th (2012) 1. Calculate the number of units (KWh) used during each period kWh September 9 th (2012) 2. Calculate the total number of units (KWh) used during the year. 3. During what period was the most electricity used, and can you explain why? 4. If one unit (1kWh) costs 8.3p, what is the average cost per day for this house?

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GCSE Science A Physics 1 Transmission of Electricity If a single 100W light bulb was switched on for a total of 4 hours, and the cost of a unit of electricity (1kWh) is 8p then….. Units used (kWh) = power (kW) time (h) = = 0.4 cost = units used cost per unit = = 3.2p This doesnt seem much, but this is for only one 100W light bulb that is on for 4 hours – how many light bulbs do you have switched on in your home during the day?

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GCSE Science A Physics 1 Transmission of Electricity Different Shoes How would todays lesson be different if it was taught by: A third world (LEDC) farmer A climate change scientist A money saving expert

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