Posterous theme by Cory Watilo

2.8

2.8

24 November 2010

10:13
· 2.8 recall that mains electricity is alternating current (a.c.) and understand the difference between this and the direct current (d.c.) supplied by a cell or battery.


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d.c. sources
· cell
· battery
· dc power pack
· dc generator

a.c. sources
· mains
· ac power pack
· ac generator