A bulb lights when current flows through it, and current flows only round a complete loop from the battery. A closed switch is a wire and an open one is a gap; a wire across a bulb takes the current away from it. Current in amps is the voltage in volts divided by the resistance in ohms. Resistors in line add; resistors side by side share the voltage, so together they are less than the smallest. Power in watts is current times current times resistance. A battery has no resistance of its own, and bulbs marked identical are the same.
3:00 on the clock, and it only runs while a question is on screen.
Questions get harder as you answer correctly and easier when you miss.
You start at the first level.
Until your first miss, every right answer jumps a whole band. After it, three right answers in a row jump a band, and a miss drops one.
A right answer scores the question's points; a wrong one costs half as many. Guessing does not pay.