## The didactics of Ohm's Law

Physically seen: each curve is a straight line,

if you look at it detailed enough.

Ohm's law

potential differenceorvoltage = strength of current × resistancewas called Ohm's Law always.

However this formula is not a law; not at all!

In factvoltage = strength of current × resistanceis nothing but a definition;

the definition of resistance.

Voltage = strength of current × resistancewould be a law

if and only if the resistance stayed constant whatever the conditions of the resistor.

However nature not dishes out ever this requirement.

Theideal resistancedoes not exist so neither doesOhm's Law.

Unfortunately voltage and strength of current are not proportional!

resistance of a resistor does not exist.The

Many teachers have been doing their best to try

to let sign by their students

the graph showing the relationship between voltage and current strength

as a straight line. I confess: I did it too.

Nature is here substantially violated and didactics is therefore misleading.

The definition of resistance

From a didactical perspective I suggest

to avoid the expressionOhm's lawand

to talk about thedefinition of resistance.

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