I have a question regarding power drain.

If you plug a device in a 240v socket and the output is 12v 10 Watts, what is the power used in amps. Do you simply divide the end wattage by the original voltage (240)?

Larry

HI Larry, the age old formula applies. Watts = Volts * Amps, so the output is 10 watts = 12 volts * 0.83 Amps.  It would be reasonable to assume that a 240v to 12v power supply would be about 80% efficient thus your input would be about 12.5 Watts ((10/80)*100), thus your input current would be about 0.052 Amps (12.5/240).

I hope this helps.

Hi

As Plendo has said the POWER used will be around 1O to 20% higher due to the conversion losses in the converter .

BUT the actual AMPs drawn could be up to 50% more. as most converters have a poor power factor, often given as PF 0.xx