Physics 12 Question!
Circuits:

I know the answer to part a and part b.

For part c use the formula = P= IV or P= (I^2)(R)

Question

Physics 12 Question!
Circuits:

I know the answer to part a and part b.

For part c use the formula => P= IV or P= (I^2)(R)

korosh23 · Answer

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korosh23 · Answer

For part c, the answer is 0.11 W. My teacher told me, but I don't understand why I have to follow this method, could you please clarify it for me. Thank you.

V3=IR3
V3=(0.33 A)(100ohms)= 3.3 v
P= IV3
P= (0.33)(3.3)=0.1089 W

anx · Answer

You're tying to find the power dissipated through the 100 ohm resistor. 
the formula you're teacher gave you basically says from top to bottom:
V3 = IR3
the current through R3 (100 ohm resistor) found in question 2 is multiplied through to find the voltage. 

Then use the power formula to find the power dissipated through the resistor
P=IV3 
P = (current)(voltage through R3) 
P= (0.33 A) (3.3V) = .1089 which rounds out to about .11W.

vincent-lyon.fr · Answer

P= (I^2)(R) leads to the same answer. It is also correct.