gcse science a physics 1 transmission of electricity learning outcomes explain in terms of energy...

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1 Transmission of ElectricityTransmission of Electricity

Learning OutcomesLearning 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)

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Key Words:Key Words:

• Power: The rate of flow of energy• Power: The rate of flow of energy

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What do you remember from last lesson?

What do you remember from last lesson?

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Power = Voltage x CurrentPower = Voltage x Current

When we send electricity through a step up transformer, it increases the voltage and decreases the 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

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.

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)

6 6 1

6 3 2

6 2 3

6 1 6

6 0.5 12

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Why do we need step down transformers?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!We need to use low voltages for safety!

Click this...

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Power = Voltage x CurrentPower = Voltage x Current

P = V x IP = V x I

PP VV II= x V = P I = P I V

V = P I = P I V

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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?

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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?

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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?

gcse science a physics 1 transmission of electricity learning outcomes explain in terms of energy...

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