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

[turbomen]

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?

 

[andyb]

turbomen, 1st find your voltage using V=IR

Then calculate your power using P=VA

 

[adamh]

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?

so your answer is 0.680000mW

 

[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?

so your answer is 0.680000mW

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.

 

[pushrod]

153mW as andyb said.

 

[turbomen]

153mW as andyb said.

What is your time from U.K.?

 

[adamh]

so it is