What does d.c. stand for? What does a.c. stand for? What do you currently know about the electricity you get from a household plug? Voltage, frequency etc…. Starter

6.1 Alternating Current

By the end of today: –You should know what is meant by direct and alternating current. –You should be able to recall the frequency of mains electricity. –Most will be able to describe in detail how an oscilloscope can be used to measure the frequency. 5.1 Electric Circuits

What is ac and dc? ect-current-vs-alternating- current/4557.htmlhttp:// ect-current-vs-alternating- current/4557.html Why is ac used? short-history-of-direct-and-alternating- current/1870.htmlhttp:// short-history-of-direct-and-alternating- current/1870.html

Copy this page Direct Alternating What about this?

What is the peak-to-peak voltage? How long (in seconds) is it for one complete wave?

Learning Tasks…. 1.Silently read pages Define, as fully as possible: Frequency Live Wire Neutral Wire Oscilloscope Y gain control Time base control 3.What is the frequency and voltage of a mains circuit? 4.Summary questions 1 and 2 page 185

6.2 Cables and Plugs

In pairs devise five questions that could have the answer: A 3 pin plug.

By the end of today: –You will be able to name all the parts of a plug and describe their function. –You will be able to explain why they are made of certain materials. –You will have had a go at wiring a plug 6.2 Cables and Plugs

Blue wireNeutral Brown wireLive Green and Earth yellow stripes Remember! B L UE bottom L eft B R OWN bottom R ight S T RIPED goes T op Copy this page

Component Function Material Reason Case Pins Fuse Cable Grip Outer Cable Inner wire Copy this page 6.2 Cables and Plugs

By the end of this lesson (or finished for homework) Produce a guide for the incompetent on ‘how to wire a plug’. You choose how to present your work.

Why does a three pin plug have three pins?

Why is one pin longer than the others?

–Pages –What is a fuse used for? How does it work? Draw a quick diagram with your explanation. –What is a circuit breaker used for? How does this work? –Why do we ‘earth’ large electrical devices? –SQ 1 and 2

6.4 Power and Potential Difference

Power Power (watts) = Energy Transformed (joules) Time (seconds) This means the more powerful something is, the more energy is transferred every second. Copy this page

Power Power (watts) = Energy Transformed (joules) Time (seconds) For example: If a bulb transforms 300 J of electrical energy into light in 3 second, the power is: P = Energy Transformed ÷Time P = 300 (J) ÷ 3 (s) P = 100 W Copy this page

Power in a circuit Power = Current x Potential Difference (watts, W) = (ampere, A) x (volts, V) P = I x V For example: If a bulb has a p.d. across it of 3.0V, and a current flowing through it of 2.0A then the power is: P = I x V P = 2.0 (A) x 3.0 (V) P = 6.0 W Copy this page

6.5 Energy and Charge

Charge in a circuit Charge = Current x Time (coulomb, C) = (ampere, A) x (seconds, s) For example: How much charge flows if a current of 2.0 A flows for 60 seconds? Charge = Current x Time Charge = 2.0 (A) x 60 (s) Charge = 120 C Copy this page

Energy in a circuit Energy Transformed = Potential Difference × Charge (joules, J) = (volts, V) x (coulomb, C) For example: How much energy is transformed when the p.d. is 30V and the charge is 2.0 C? Energy = Potential Difference × Charge Energy = 30 (V) x 2.0 (C) Energy = 60 J Copy this page