Question

Ideal vs real battery

a. An ideal battery doesn't exist, are all batteries real?

b. Is the chemical reaction the reason why there is internal resistance?

c. When learning ohms law why to use examples of ideal batteries?

Answer 1

a) An ideal battery is one in which there is no internal resistance. Since it is not possible to have completely zero internal resistance, so it is not possible to have ideal batteries. Hence, all batteries that we actually use are real.

b) Resistance is the ability of the battery to hinder flow of electrons through it. There exists no material with absolute zero resistance, due to the internal structure of the material. Hence, the materials we use in a battery have their own inherent internsl resistance. The chemical reaction that occurs during the operation of a battery, is responsible for this internal resistance showing up in how the current flows through it.

c)

Ohm's Law

V = IR

where

V = Potential Difference

I = Current through the circuit

R = resistance

So, Learning Ohm's law is easier through ideal batteries where there is no term for voltage drop.

If we use real batteries the Ohm's law has to modified to include the voltage drop as a result of the internal resistance

The expression that we have to deal with then is

= Ir + V

where

= emf

I = current

r= internal resistance

V = voltage drop