Describe current/PD characteristics of a filament lamp practical?

Just like in the resistor practical, adjust the variable resistor and read the potential difference and current, then do this for a range of values with the battery in the forward and reverse direction. Plot a graph of the current against the potential difference, the results should be a straight line passing through zero with a curve at the beginning and the end of the line, this is because when the current increases the temperature of the filament lamp increases. An increased temperature that causes the resistance to increase. And the same shaped graph will occurs when the direction of the potential difference is changed.