Question

As an auto mechanic, you need to determine the emf and internal resistance of an old battery. you perform these two measurements: (1) you apply a voltmeter to the battery\'s terminals and read 11.8 v. (2) an ammeter applied to the terminals indicates 16.5
a. what are the battery\'s emf and internal resistance?

Answer 1

We are asked to solve for the internal resistance of the electromotive battery and to answer this we need to apply Ohm's Law which is Voltage is equal to the product of measured current and resistance (V = IR). Thus, to solve for resistance we have it R = V/I where voltage was measured and value is equal to 11.8 volts and current was also measured and the value is 16.5 amperes.

Solving the internal resistance, we have it:
R = V/ I
R = 11.8 volts / 16.5 amperes
R = 0.715 ohms

The answer is 0.715 ohms.