How to Calculate EMF and Internal Resistance in a Circuit?

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To calculate the EMF and internal resistance of a cell, two scenarios are presented involving resistors in series and parallel. In the first case, a cell supplies 1.2A through two 2-ohm resistors in parallel and 0.4A when connected in series, leading to the equation EMF = 1.2(1 + Ri). The second scenario involves a 2-ohm resistor with a current of 0.25A, which increases to 0.3A when a second 2-ohm resistor is added in parallel. By setting up two equations based on these conditions, both the EMF and internal resistance can be solved. Understanding these relationships is crucial for accurately determining circuit parameters.
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Homework Statement


Hi, my first post here. :smile:
Anyway I am struggling with this homework, can someone help me out, show me what to do please.

1)a cell can supply a current of 1.2A through two 2ohm resistors connected in parallel. When they are connected in series the value of the current is 0.4A. calculate the EMF and the internal resistance of the cell.

2) A cell is joined in series with a resistance of 2ohms and a current of 0.25A flows through it. When a second resistance of 2ohms is connected in parallel with the first the current through the cell increases to 0.3A. What is the EMF, and what is the internal resistance of the cell?

I really have no idea what to do, but i need to do this very quickly.

Any help would be greatly appreciated
 
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a cell can supply a current of 1.2A through two 2ohm resistors connected in parallel.

EMF = 1.2 ( 1 Ohm + Ri )

When they are connected in series the value of the current is 0.4A

You write the equation.

Two equations and two unknown variables ( Ri and EMF ). Solve !
 

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