Question

What is ohmic resistance? What is nonohmic resistance?

Why does the resistance increase in the nonohmic resistance as Voltage increases?

What is the physical property of slope (change in V/ change in I) on the V versus I plot?

Is the resistance positive or negative for most metals? Does it depend on whether the voltage is positive or negative? Explain.

Answer 1

Ohmic resistance:- Ohmic resistance are linear slope between voltage v/s current graph. Actually Ohmic resistance are the resistance of those circuit which follows the ohm's law and doesnt depeds on variation of temperature. Also it is linear slope between voltage and current.

Nonohmic resistance:- It is not like ohmic resistance because its not follow ohm's law perfactely. Its slop is nonlinear in nature. Basically it is affected by some physical properties like temperature and pressure.

If you increase the voltage than the temperature of the conductor will increase due to effect and if it is nonlinear or nonohmic resistance than it will affected by temperature and the resistance will by vary.

R = V/I

so, R is proprtional to Voltage.( Remember it is not a case of ohm's law. It is due to nonlinearity properties of resistance.)

The physical properties like temp. and pressure must be unchanged for determing slope curve between voltage v/s current graph.

For the most metal resistance is positive due to its positive coefficient proerties of metal. but some elements like silicon(si) and germenium(Ge) have negative coeff. resistance.

Hope this explanation help you.