Question

You are working with a team to test the efficiency of aircraft trainer batteries. At starting, what is the current drain on a 12 V aircraft trainer battery if the resistance of the starting motor is 40 mΩ? In addition to the answer and your work, explain to the team how adjusting either the voltage or resistance would affect the drain.  

Answer 1

Given voltage of the battery = V = 12 Volts

Resistance of the starting motor= R = 40 milli Ohms = 0.04 ohms

Current drain = I = V / R = 12 / 0.04 = 300 Amperes

The explanation for the Current drain,

A scientist named J.Simon Ohms found that the current is directly proportional to the voltage at a constant resistance.

This is called as Ohms Law.

Mathematically it is represented as,

V = I * R

where

V= Voltage in volts

I = Current in Amperes

R = Resistance in Ohms

Now from the Ohms law, we can write,

I = V / R

From the above equation, we can conclude two things,

1-->The current drain will increase with an increase in voltage

2-->The current drain will reduce with increase in resistance.

Following the above two conclusion statements, the voltage and the resistance changes will affect current drain.