Suppose you are given such a battery eg an AA battery descri

Suppose you are given such a battery (e.g. an AA battery), describe in detail how would you determine (measure) the two parameters r and E (you can use voltmeter, ampere meter, additional resistors, etc.). There is a limitation: the maximum current that can pass through the battery is 0.2 A. The requirement for your descriptions is as follows: another student can follow your description to perform the measurement as well as the calculations for getting the values of r and E.

Solution

Given to describe in detail how to know the parameters of E and r of AA battery .

We can use voltmeter or ammeter and additional resistor . Now connect additional variable resitor across the battery which is initially very large and slowly vary the resistance of variable resistor to get current throught that resistor of 0.2 A.

Now let the variable resistor be of value of R which draws a current of i=0.2 A from the batter;

Now applying KVL

E = i*r + i*R ; ---------(1)

Here unknown are two to find two unknows we need to have two equations.

If we fix the internal voltage E, then we can measure internal resistance r .

Thus we can measure E and r of a battery.