A miniature torch bulb draws a current of 200 mA when connected to a 1.5 V cell.
(i) Calculate the resistance of the bulb filament under these conditions.
(ii) The same bulb is now connected to a 3.0 V power supply. Assuming the filament resistance remains unchanged, calculate the new current through the bulb.
(iii) Determine the potential difference that must be applied across the bulb so that the current through it is exactly 0.5 A.