1. GCSE Science A Physics 1 Transmission of Electricity Learning Outcomes Explain in terms of energy efficiency and safety, why electricity is transmitted at high voltages but used at low voltages. Investigate the operation of ‘step up’ and ‘step down’ transformers. Select and use the equation Power = Voltage x Current (P=V x I) Explain in terms of energy efficiency and safety, why electricity is transmitted at high voltages but used at low voltages. Investigate the operation of ‘step up’ and ‘step down’ transformers. Select and use the equation Power = Voltage x Current (P=V x I)

2. GCSE Science A Physics 1 Transmission of Electricity Key Words: Power: The rate of flow of energy

3. GCSE Science A Physics 1 Transmission of Electricity What do you remember from last lesson?

4. GCSE Science A Physics 1 Transmission of Electricity Power = Voltage x Current When we send electricity through a step up transformer, it increases the voltage and decreases the current This means that the power always stays the same We want to send electricity at as low a current as possible because this means less energy will be lost in the power lines as heat. Power (Watts)Voltage (Volts)Current (Amps) 661 632 623 616 60.512

5. GCSE Science A Physics 1 Transmission of Electricity Why do we need step down transformers? Step down transformers lower the voltage and raise the current (the power stays the same) Step down transformers lower the voltage and raise the current (the power stays the same) We need to use low voltages for safety!

6. GCSE Science A Physics 1 Transmission of Electricity

7. GCSE Science A Physics 1 Transmission of Electricity Power = Voltage x Current P = V x I P P V V I I =x V = P I = P I V V = P I = P I V

8. GCSE Science A Physics 1 Transmission of Electricity Example 1: My laptop has a power rating of 76W, it uses 4A of current. What Voltage does my laptop require? Example 1: My laptop has a power rating of 76W, it uses 4A of current. What Voltage does my laptop require?

9. GCSE Science A Physics 1 Transmission of Electricity Example 2: The average home uses around 1000W of electricity. Houses use electricity at 240V. What is the current used by the house? Example 2: The average home uses around 1000W of electricity. Houses use electricity at 240V. What is the current used by the house?

10. GCSE Science A Physics 1 Transmission of Electricity Today, you guys are going to be the teachers. A select few of you will come to the front, sum up the lesson, and then question the class! Who’s brave enough to take up the challenge? Today, you guys are going to be the teachers. A select few of you will come to the front, sum up the lesson, and then question the class! Who’s brave enough to take up the challenge?