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If the secondary current from a 50 watt light supplied through a 240 volt to 12 volt transformer is approx 4 amps what is the input current on the 240 volt supply side.

2007-01-27 18:23:33 · 3 answers · asked by WM 2 in Science & Mathematics Physics

3 answers

WM,

you didn't specify the kind of light, so I assume a standard resistive element. The input power on a transformer primary is approximately the same as on the secondary. I=P/V, or I=50watt/240volt which is about 0.21amp. If you allow for 20% loss in the transformer, then you get 0.25amp.

2007-01-27 18:38:23 · answer #1 · answered by GTMCFARLAND 2 · 0 0

If voltage is stepped down by a factor of 20 (240/12) then current is stepped up by the same factor.
I (primary) x V (primary) = I (secondary) x V (secondary)
I (primary) x 240 = appx .4 x 12
Or another way 50 watts / 240 volts = I (primary) = 0.203 amps.

2007-01-27 18:46:32 · answer #2 · answered by a simple man 6 · 0 0

Actual output power is 12 x 4 = 48 watt.

Input power = 48 watt.

Input current = 48 / 240 = 0.2 A.

2007-01-27 19:43:40 · answer #3 · answered by Pearlsawme 7 · 0 0

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