Help

[dome406]

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.

[Geoff]

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.

[dome406]

Thanks very much