Force, Energy

1
Force, Energy Communication

• Lesson 10 11
• TRANSFORMERS

2
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

3
NO! Not one of these!
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Thats better, one of these!
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PHYSICS TEXT BOOK

• Turn to page 94

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PHYSICS TEXT BOOK

• Turn to page 94
• Come round the front bench!

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Really they are just too camp!
8
Transformers

• The job of a transformer is to change the voltage
  in a circuit.

9
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

10
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

11
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.

12
This is a STEP-UP transformer (more coils in the
secondary than primary coil)
13

• Collect an experiment sheet and carry out your
  own investigation into transformers.

14
Calculating the output voltage

• The output voltage can be calculated using this
  formula

15
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
16
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?

17
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

18
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)

19
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

20

• Collect The transformer data analysis
• Carry out all the exercises on this sheet.

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• 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.

22
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