Physics

Failures of ohm's law ohm's law is not a fundamental law .in many cases  it fails.  Ohmic conductor : The conductor which obey ohm's law are called ohmic conductor. eg. pure metals, cuso4 solution etc for ohmic conductor; 1.V-I graph is straight line and passes through origin. 2. the direction of current is reverse, if P. D(V)  is reverse. but magnitude of I remains same. 3. for a potential difference,  there is only one value of current. Non ohmic conductor : the conductors which do not obey ohm's law are called non ohmic conductors eg. junction diode, water voltmeter, vaccum tube etc for non ohmic conductor 1.graph B/w V&I is not straight line  i. e V/I not equal to constant. 2.if V-I graph is a straight line it does not passes through the origin. eg. water voltmeter. 3. current can have more value for a given potential difference i. e resistance does not have a constant value. 4.the relation B/w V-I depends upon the sign of V i. e cur...