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 14th September 2005, 07:34 PM #1 dome406   diyAudio Member   Join Date: Mar 2004 Location: uk Help I have just started A-level electronics and am slightly confused at this question, I know it is very simple but it is not explained in my textbook, hope you dont mind me asking. How would you calculate it. Calculate the maximum safe current through a resistor of: a) 100Ohm 1W Thanks very much.
 14th September 2005, 09:10 PM #2 Geoff   diyAudio Member   Join Date: Apr 2001 Location: UK W = V x I Ohms Law: V = I x R so W = (I x R) x I = I^2 x R or I = sqrt(W / R) so I = sqrt(1 / 100) = 0.1A The theoretical maximum current is therefore 0.1A but in practice you would never run a component anywhere near to its maximum rating (which could be specified at a temperature rise of up to 70°C). Realistically, you would limit the current through this resistor to 50mA or less.
 14th September 2005, 09:21 PM #3 dome406   diyAudio Member   Join Date: Mar 2004 Location: uk Thanks very much

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