Non-ohmic behaviour is particularly advantageous in applications like dimming lights and regulating power supply. For instance, in a dimmer switch, the non-linear relationship between current and voltage in a non-ohmic conductor, such as a silicon-controlled rectifier (SCR) or TRIAC, is utilised to vary the intensity of light. By adjusting the resistance dynamically, these components control the portion of the AC waveform that reaches the light bulb, effectively changing its brightness. Non-ohmic devices are integral in various electronics, including radios and amplifiers, where variable resistance is required to modulate signals and control power flow effectively.

The physical size of a resistor is often related to its power rating rather than its resistance. Larger resistors can dissipate more heat, allowing them to handle higher power without overheating or failing. The power rating, measured in watts, indicates how much power the resistor can handle safely. It's not directly correlated with the resistance, as resistors of the same size can have different resistances. In circuits where higher power dissipation is expected, larger resistors are employed to manage the heat effectively, ensuring the stability and safety of the electrical and electronic systems.

Ohmic values are measured and verified experimentally by measuring the current flowing through a component at different applied voltages and plotting the I-V (current-voltage) characteristics. For ohmic conductors, this plot should be a straight line passing through the origin, indicating a constant resistance as per Ohm’s Law (V=IR). This can be conducted using a simple setup including a variable power supply, an ammeter to measure current, and a voltmeter to measure the potential difference across the component. The gradient of the resulting straight line on the I-V plot gives the resistance, further confirming the ohmic nature if it remains constant for varying voltages and currents.

Resistors are crucial in protecting electronic components by controlling the amount of current that flows through a circuit. By applying Ohm’s Law, V = IR, we can appreciate that for a given voltage, increasing resistance reduces current. This function is critical in protecting sensitive components that could be damaged by excessive currents. For example, in a simple circuit with a LED, a resistor is often placed in series to limit the current flowing through the LED, preventing it from burning out due to excessive current while ensuring it operates efficiently within its specified ratings.

Temperature significantly impacts the resistance of both ohmic and non-ohmic conductors. For ohmic conductors, typically metals, an increase in temperature leads to an increase in resistance. This is because, as temperature rises, the metal ions in the conductor vibrate more vigorously, impeding the flow of electrons and increasing resistance. On the other hand, for non-ohmic conductors, especially semiconductors, an increase in temperature typically decreases resistance. Higher temperatures provide energy to free more charge carriers, increasing their number and, consequently, reducing the resistance as the material becomes more conductive.