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Worksheet: Transformers
Transformers (Enquiry)
Aim
In this investigation you will measure the Secondary voltage of a simple transformer as you vary the
number of windings in the secondary coil. You will find this investigation particularly useful to gain a
better understanding of the principles involved in step up transformers.
Equipment
- Simple D.C. motor
- Digital video camera
- Variable resistor, or potentiometer
- Ammeter
- D.C. power supply (12V output)
- Switch
- Crocodile clips
Safety
- Wires can become very hot if too much current is flowing through them, so ensure the Primary
voltage is not too high and that you do not add too many windings in the secondary coil.
- If you are using crocodile clips to connect the windings to the power supply, make sure they don’t
touch each other and cause a short circuit.
Method
A.C.
1.
2.
3.
4.
5.
V
Look at the diagram above to set up the equipment
Start with the same number of windings on the Primary and Secondary coils, say 10
Set the A.C. Voltage generator so that it gives a Primary Voltage of about 1.0 V
Read and record the Secondary Voltage induced in the secondary coil
Increase the number of windings in the Secondary coil and repeat your measurements until you
have collected enough data
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Worksheet: Transformers
Table of results
Complete the table of results below and add the units to the column labels.
N1 (Primary Coil)
V1 (Primary Voltage)
N2 (Secondary Coil)
V2 (Secondary Voltage)
Analysing your results
Now draw a graph of the Secondary Voltage against the number of windings in the Secondary coil and
answer the following questions.
Questions
1. Is there a pattern in the number of windings in the Secondary Coil and the Secondary Voltage?
Describe the pattern, if you found one.
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2. Calculate the gradient of your graph.
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Worksheet: Transformers
3. How does the gradient of your graph compare with the fraction
𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑉𝑜𝑙𝑡𝑎𝑔𝑒, 𝑉1
𝑃𝑟𝑖𝑚𝑎𝑟𝑦 𝑛𝑜 𝑜𝑓 𝑤𝑖𝑛𝑑𝑖𝑛𝑔𝑠, 𝑁1
?
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4. Can you suggest an equation to describe the relationship between V1, N1, V2 and N2?
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