Ohmic and non-Ohmic conductors AQA Alevel physics

[@chaolin9089]

I cannot say how impressive this presentation is, this is possibly the clearest and informative description of ohmic and non ohmic conductors I could ever ask for, thank you very much for this, and thanks for saving my GCSEs.

[@leonardjalba9310]

Sorry but resistance is the ratio of voltage to current isn’t it so to calculate resistance of current voltage graph you don’t use gradient to calculate resistance

[@TLPhysics]

Hi, if you are given graphical data of the voltage vs current of how your component works and it is non ohmic (IE not a straight line because the resistance changes for arious reasons) You can work out the gradient which is V/I at a point and find out the resistance of the component at that situation (IE current flowing through it) We tend to use this fact that the resistance of the component is the gradient of a V vs I when the resistance is not constant! Hope that helps

[@z_6077]

@@TLPhysics wouldn’t the graph of V against I for a diode be a reciprocal instead of the graph touching y axis?

[@TLPhysics]

Depends on are you talking a real diode or a "ideal" one. Ideally a diode lets NO current through until you reach the threshold voltage. In reality this is not true. You almost represent that on the ideal diode by the curve from no current to max current. (This curve section of responce from nothing to all out is actually used in componenets called MOSFETS to make a MOSFET a variable resistor, but that is definately not on main spec) So the graph I have drawn is to show the characteristics of an ideal diode not a real one (this is where you deal with leakage etc) Hope that helps

[@techdose7230]

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