Many thanks for the reply and explanation. This is a great example of how there's always something new to learn! I was viewing Ohm's Law in a very simplistic way as a straightforward arithmetic equation. A quick look at Wikipedia put me straight in defining it as I∝V which is a linear relationship. Obviously non linear materials (and of course semiconductor devices) do not follow this relationship and I'm familiar with the V/I curves of various diodes etc. I had in my head this image from Z's post of the current increasing with decreasing voltage at a fixed temperature which would require the resistance to drop without temperature change! Now the fog has cleared somewhat I do appreciate that the non linear (nonohmic) behaviour means in this case I is not proportional to V.
The actual power developed in the resistance of the cable can still of course be calculated using Ohm's law providing we know the material characteristics and therefore resistance at a specified temperature and the voltage applied.
Many thanks for the reply and explanation. This is a great example of how there's always something new to learn! I was viewing Ohm's Law in a very simplistic way as a straightforward arithmetic equation. A quick look at Wikipedia put me straight in defining it as I∝V which is a linear relationship. Obviously non linear materials (and of course semiconductor devices) do not follow this relationship and I'm familiar with the V/I curves of various diodes etc. I had in my head this image from Z's post of the current increasing with decreasing voltage at a fixed temperature which would require the resistance to drop without temperature change! Now the fog has cleared somewhat I do appreciate that the non linear (nonohmic) behaviour means in this case I is not proportional to V.
The actual power developed in the resistance of the cable can still of course be calculated using Ohm's law providing we know the material characteristics and therefore resistance at a specified temperature and the voltage applied.
