Please read carefully, I don\'t need any of these worked out:) (a) Find the equi

Question

Please read carefully, I don't need any of these worked out:)

(a) Find the equivalent resistance between point a and b.
?

(b) If a voltage of 31.3 V is applied between points a and b, find the current in each resistor.
12 ? A
6 ? A
5 ? A
4 ? A
8 ? A

Okay, so there's actually several versions of this already answered, and I already understand how to get the I (current) for every R (resistor) in parallel; what I don't get is that in every explanation, people just take for granted that the I through the 5 ohm resistor = I of the system (2.68 in this case). Why isn't it V/R like everywhere else?

Explanation / Answer

Current is always constant in series combination of resistors.

Consider it this way,

Current is rate of flow of charge, and this flow is charge is caused when potential differenge is there/applied. Saying the current will be different in series would mean that current is charge is accumulating somewhere in the circuit, or the charge is flowing slow in some places while fast in other place.

so, sum of current through 12 and 6 resistors = current through 5 resistor = sum of current through 4 and 8 resistors.

Current in the circuit will be equal to V/R, where R is equivalent resistance of the circuit.

Also, the relation V/R is always satisfied. In series, the potential difference (v) is dependent on resistance.

For example, potential difference across 5 resistor = 31.3*5/(4+5+2.6667) = 13.414 V

now the current through it would come out to be I = V/R = 13.414/5 = 2.6828 A

which is same as current through the whole circuit-

I = V/R = 31.3/(4+5+2.667) = 2.6828 A

note that 4 is equivalent resistance of parallel combination of 12 and 6 .

note that 2.667 is equivalent resistance of parallel combination of 8 and 4 .

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