Draw the I-V curves of both an ideal resistor and a filament bulb. Explain the key features of both.

Plot: I-V curve of an ideal resistor is a straight line with a positive gradient passing through (0,0)The I-V curve of an ideal resistor is a straight line because ideal resistors strictly obey Ohm's law (V = IR). The gradient is constant because the resistance does not change. The line should pass through the origin because no current can flow with zero applied potential difference.Plot: The I-V curve of a filament bulb is a sub-linear line passing through (0,0)The I-V curve of a filament bulb has a decreasing gradient as voltage increases. This is because as more voltage (or current) is applied, the temperature of the filament increases. The atoms making up the filament will therefore increase in energy and an increase in their movement. The rate of collisions between the electrons and the lattice will increase. The resistance of the filament therefore increases. The line should still pass through the origin because no current can flow with zero applied voltage.