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Force, Energy & Communication. Lesson 10 & 11 TRANSFORMERS. Lesson Objectives. Appreciate the role of transformers Understand how to make and use a transformer To be distinguish between a step-up and step-down transformer. To understand and be able to use the transformer equation.
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Force, Energy & Communication Lesson 10 & 11 TRANSFORMERS
Lesson Objectives • Appreciate the role of transformers • Understand how to make and use a transformer • To be distinguish between a step-up and step-down transformer. • To understand and be able to use the transformer equation
PHYSICS TEXT BOOK • Turn to page 94
PHYSICS TEXT BOOK • Turn to page 94 • Come round the front bench!
Transformers • The job of a transformer is to change the voltage in a circuit.
Transformers • A step down transformer REDUCES the voltage in a circuit. • The input voltage is higher than the output voltage. • e.g. transformers found in electrical sub-stations
Transformers • A step up transformer increases the voltage in a circuit. • The input voltage is lower than the output voltage. • e.g. transformers used to convert USA voltage to UK voltage
What a transformer is made of • Consists of two coils of wire wrapped around a soft iron core. • The coil attached to the INPUT voltage is called the PRIMARY coil • The coil attached to the OUTPUT voltage is called the SECONDARY coil.
This is a STEP-UP transformer (more coils in the secondary than primary coil)
Collect an experiment sheet and carry out your own investigation into transformers.
Calculating the output voltage • The output voltage can be calculated using this formula:
Calculating the output voltage • The output voltage can be calculated using this formula: secondary (output) voltage = no. of turns on secondary coil primary (input) voltage no. of turns on primary coil
Worked example • A transformer has 960 turns on the primary coil and 16 turns on the secondary coil. The primary coil is connected to 230V a.c.. What will be the output?
Worked example • A transformer has 960 turns on the primary coil and 16 turns on the secondary coil. The primary coil is connected to 230V a.c.. What will be the output? • secondary voltage = 16 230 V 960
Worked example • A transformer has 960 turns on the primary coil and 16 turns on the secondary coil. The primary coil is connected to 230V a.c.. What will be the output? • secondary voltage = 16 230 V 960 So the secondary voltage = 230 X (16/960) =
Worked example • A transformer has 960 turns on the primary coil and 16 turns on the secondary coil. The primary coil is connected to 230V a.c.. What will be the output? • secondary voltage = 16 230 V 960 So the secondary voltage = 230 X (16/960) = 3.9 V
Collect “The transformer – data analysis” • Carry out all the exercises on this sheet.
Collect “The transformer – data analysis” • Carry out all the exercises on this sheet. • HW • Complete the questions on the sheet “TRANSFORMERS” – hand in on Thursday.
Lesson Objectives • Appreciate the role of transformers • Understand how to make and use a transformer • To be distinguish between a step-up and step-down transformer. • To understand and be able to use the transformer equation