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## Homework Statement

To find the emf and internal resistance of an unmarked battery you are given two resistor of value 5.0(ohms) and an ammeter. When the resistors are connected in parallel the current drawn from the battery is 2.0A. What are the e.m.f and internal resistance of the battery?

Am i going right?

## Homework Equations

E = IR = Ir

## The Attempt at a Solution

Series

R = 5(ohms) + 5(ohms) = 10(ohms)

Parellel

1/R = 1/5 + 1/5 = 2/5

R = 2.5(ohms)

E = 0.75*10 + o.75*r

E = 7.5 + 0.75r ------- (1)

E = 2*2.5 + 2r

E = 5 + 2r ---------- (2)

7.5 + 0.75r = 5 +2r

2.5 = 1.25r

2(ohms) = r

there for r in equation 1 gives

E = 7.5 + 0.75(2)

= 9V