- Transformers
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Objectives:
- To be able to do transformer calculations
Timing: 1 lesson
Write down the equation from last year relating power, voltage and current. Power into a transformer = power out (in a perfect world). Now re-write this in terms of voltage across and current in the primary and secondary coils. http://www.s-cool.co.uk/ may help you. Can you remember from last year why electricity is transmitted using high voltage and low current?
Power is lost in reality because of energy transfers in the cables due to resistance. Write down an equation relating power, resistance and current. How are power and current related?
Do transformers work on AC or DC? Why? Where are they found and what do they do?
You need to know the difference in structure of a step-up and step-down transformer and how each one works. You also need to find out the equation relating number of turns to the voltage.
An isolating transformer is used in a shaving point in a bathroom. There don't seem to be many easy-to-understand articles on them on the internet but have a little read of the relevant sections in the following two sites to get an idea of how one works: http://www.olsun.com/glossary.html#I and http://www.usyd.edu.au/. Why is one needed in the bathroom? Why does it make the socket safe to use in the bathroom? What can you say about the number of turns on the primary and secondary coils?
You could do the following worksheets:
