Why does a transformer only work with an alternating current?
Because a changing magnetic field is required to induce an alternating current in the secondary coil. A direct current induces a constant magnetic field
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What does a transformer do?
Changes the size of an alternating potential difference.
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What does a basic transformer consist of?
A primary coil and a secondary coil (that are both insulated) which are both wrapped around a soft iron core.
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How does a transformer work?
1)Transformer consists of Vp and Vs both wrapped around a soft iron core 2) AC passes through Vp, producing an alternating magnetic field through iron core 4)Alternating magnetic field passes through Vs 5)Creating an alternating pd in secondary coil
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How could you make a model transformer for a question?
Firstly explain set up of a transformer, then attach Vp to a 1V ac power supply and Vs to a 1.5V bulb. See that enough turns of Vs will cause the bulb to light up.
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What is a step up transformer?
Where the secondary coil has more turns than the primary coil so that the potential difference across the secondary coil is greater than the potential difference across the primary coil.
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What is a step down transformer?
Where the secondary coil has less turns than the primary coil, and therefore the potential difference across the secondary coil is less than the potential difference across the primary coil.
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Can electrical current flow between the coils in a transformer?
No!
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What are switch mode transformers used for?
Small appliances, such as mobile phone chargers.
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How much power do switch mode transformers use in comparison to a regular iron core transformer?
Very little. But no load is applied (load= when your phone is not charging and it is still in the socket)
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What is the frequency of a switch mode transformer in comparison to a regular transformer?
Regular transformers have a frequency of 50 Hz, however, switch mode transformers have a very high frequency of 50,000Hz - 200,000Hz
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Why are switch mode transformers good as mobile phone chargers?
They are much lighter and smaller than regular transformers. They use very little power when no load is applied (no electrical device attached)
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Why is a high potential difference wanted in the National Grid?
Higher potential difference = greater efficiency, because otherwise more current would be needed to deliver the same amount of power. Greater current= more energy lost through cables via heat.
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Other cards in this set
Card 2
Front
What does a transformer do?
Back
Changes the size of an alternating potential difference.
Card 3
Front
What does a basic transformer consist of?
Back
Card 4
Front
How does a transformer work?
Back
Card 5
Front
How could you make a model transformer for a question?
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