Physics A Level
Chapter 10: Resistance and resistivity 10.2 Ohm’s law
Physics A Level
Chapter 10: Resistance and resistivity 10.2 Ohm’s law
For the metallic conductor whose I–V characteristic is shown in Figure 10.2, the current in it is directly proportional to the p.d. across it. This means that its resistance is independent of both the current and the p.d.
This is because the ratio is a constant. Any component that behaves like this is described as an ohmic component, and we say that it obeys Ohm’s law. The statement of Ohm’s law is very precise and you must not confuse this with the equation $\frac{V}{I} = R$.
A conductor obeys Ohm’s law if the current in it is directly proportional to the potential difference across its ends.
Question
2) An electrical component allows a current of $10 mA$ through it when a voltage of $2.0 V$ is applied.
When the voltage is increased to $8.0 V$, the current becomes $60 mA$. Does the component obey Ohm’s law? Give numerical values for the resistance to justify your answer.