Build a simple circuit where a flashlight bulb is powered by two batteries. See if you can use the potentiometer to raise the voltage to between 0 and 3 Volts. Each battery supplies 1.5 V, so you won't be able to go higher than that. What happens to the brightness of the bulb as you increase the voltage? Draw the circuit in pictorial form, and draw its representation in schematic form (see diagram below)