current electricity

The answer is option B

Clearly, the conductor doesn't obey Ohm's Law as the current is not proportional to the applied voltage, i.e. doubling the applied voltage doen't double the current.

Read from the graph, at voltage = 3v, the current is 300mA(= 0.3 A), hence resistance = 3/0.3 ohms = 10 ohms




2010-01-02 00:13:35 補充：
Resistance is defined as the ratio of voltage to current, NOT the change of voltage to the change of current.