# Ohms law problem

1. Nov 7, 2007

1. The problem statement, all variables and given/known data
Calculate the equivalent resistance of the network shown in the diagram. The resistances are: R1 = 12 ohm, R2 = 5 ohm, R3 = 15 ohm, and R4 = 15 ohm.

no prob here

Req = [(1/12)+(1/5)+(1/15)]^-1 + 15 = 17.86ohm

When a battery with E = 6 V and zero internal resistance is attached across this network, what current flows through resistor R1?

2. Relevant equations
Cant figure out if the current thru R1 is actually Req or R1.
When i use V=IR none of the answers come out correct.

3. The attempt at a solution

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2. Nov 7, 2007

### Staff: Mentor

To find the current through R1, find the voltage across it. Hint: First find the voltage drop across R4.

3. Nov 7, 2007

why do i need to know voltage drop across r4?
also does it matter which dorection the current is going?

4. Nov 7, 2007

### Staff: Mentor

Because the voltage across R1 + the voltage across R4 adds up to the total voltage.
No, that just depends on which way the battery was connected.

5. Nov 7, 2007