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# How much power will a resistor rated at 1/2 w...?

Discuss How much power will a resistor rated at 1/2 w...? in the Electrical Forum area at ElectriciansForums.net

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#### turbomen

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How much power (in mW) will a 680W resistor rated at ½ W dissipate when it conducts a current of 15 mA?

Could you tell me how can you get the answer?

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#### andyb

##### -
Arms
Esteemed
turbomen, 1st find your voltage using V=IR

Then calculate your power using P=VA

A

ressistance is measured in ohms to have the rating in W you must already know the voltage and if that is the case and this is the only ressistor in the circuit then you already know how much will be dissapted?

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T

#### turbomen

ressistance is measured in ohms to have the rating in W you must already know the voltage and if that is the case and this is the only ressistor in the circuit then you already know how much will be dissapted?

Thank you for your kind reply. But it is a multiple choice question: the answer can be 4.0 mW, 10.2 mW, 153.0 mW, 432.5 mW or 500.0 mW.

P

#### pushrod

153mW as andyb said.

T

#### turbomen

A

so it is

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