For a circuit shown in the figure, all quantities are accurate in 3 significant figures. What is the power dissipated in 2-ohm resistor?

Question

anonymous · Answer

attachment

ganeshie8 · Answer

$P = I^2R$

compute current in top branch, and plugin above ?

anonymous · Answer

should i include the 4-ohm resistor for computing the current?

anonymous · Answer

how did you know if it's series btw? XD

ganeshie8 · Answer

yes first i would start with calculating total current

anonymous · Answer

for the total current, i got 2.02. am i correct?

ganeshie8 · Answer

you can identify 4 is in series by noticing that only one end is tied to that parallel branch

anonymous · Answer

with that 2.02, so the power is 8.16W but the correct answer is 3.56W. idk why.

ganeshie8 · Answer

(2+1) is in parallel with (5+1) 
so equicalent resistance = 15/8

this is in series with 4

so total resistance = 15/8 + 4

ganeshie8 · Answer

total current I = V/R = 12/5.875 = 2.04

anonymous · Answer

wait! slow down. lol. how did you get 15/8? XD

ganeshie8 · Answer

ok, lets go step by step

anonymous · Answer

uh. is it wrong if i calculate the in parallel first? like (2*5)/2+5 and (1*1)/1+1? then calculate their resistance in series?

anonymous · Answer

*them

ganeshie8 · Answer

we are trying to find total current,
so we need to find total resistance first.

(2+1) is in parallel with (5+1)

ganeshie8 · Answer

thats wrong. we need to simplify series first. as BOTH (2+1) are forming series

ganeshie8 · Answer

and (5+1) are forming series

ganeshie8 · Answer

both (2+1) and (5+1) are forming parallel

anonymous · Answer

ahh. i see. then?

ganeshie8 · Answer

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