Why is resistance defined as V/I and not I/V?

[sreerajt]

Voltage(V) is proportional to current(I). And so V=(a constant)*I. That constant is known as resistance(R), where R=V/I. Why can't we write that I proportional to V and then write R=I/V??

 

[jtbell]

Why can't we write that I proportional to V and then write R=I/V??

We can. We simply have to give this proportionality constant a different name and symbol so that we don't confuse people.

http://en.wikipedia.org/wiki/Electrical_conductance

 

[NascentOxygen]

Voltage(V) is proportional to current(I). And so V=(a constant)*I. That constant is known as resistance(R), where R=V/I. Why can't we write that I proportional to V and then write R=I/V??

We write G=I/V
and the units of G used to be known as mhos (that's Ohms spelled backwards) with symbol an upsidedown Ω (omega).

Nowadays, the units have been renamed an uninteresting "siemens".

 

[Sefrez]

Because that is not the reality? I know VR != I. If that were the case, current would increase with resistance. Which completely disagrees with our current definition of resistance!

EDIT:
Oh, I misinterpreted your post. Well, yes, of course you could. But R would be a different quantity, as the right side of the equation implies.

 

[sreerajt]

Could you please make it clear?

 

[f95toli]

Resistance (R) is DEFINED to be what it is. There is no "reason" for it, it is just a convention.

And again, the quantity I/V already has a name of its own: conductance (G), which has the units of Siemens.

 

[sophiecentaur]

I think you means 1/R.

Remember: R is 'how hard'
and G is 'how easy'.

 

[sreerajt]

Thanks f95toli.. i think your answer is quite satisfying for me...