- #1

Draconifors

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## Homework Statement

In the circuit shown in the figure above, the ammeter reads 3.4 A and the voltmeter reads 6 V. Find the emf ɛ and the resistance R.

## Homework Equations

Ohm's law; V= I*R

EMF equations: ε=I*r+I*R

ε=I*r+V

## The Attempt at a Solution

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I got the resistance of R right: It's 5.29Ω. To do that, I found the current in the 2Ω resistor (6V/2Ω=3A).

Then, I know that since the 2Ω and the 4Ω resistors in are in series, the current in the two of them are equal. (4Ω*3A=12V).

Then, I add up the two voltages (=18V), and solve for R using V=I*R, which gives me 18/3.4 =

**5.2941Ω**.

However, when it comes to finding the emf, none of my answers are correct. I've tried "reducing" the circuit so it becomes 3 resistors in parallel (4Ω,2Ω and R on one side, 1Ω and the battery in the middle, and the 2 3Ω ones on the other side). However, this doesn't seem to give me the right answer. At first I thought it might be 6 volts since circuits in series are supposed to have the same voltage everywhere, but then I tried rationalizing it and it didn't work.

Any push in the right direction would be greatly appreciated!