Translations:AY Honors/Model Rocketry/Answer Key/42/en
From Pathfinder Wiki
In this launcher, power is supplied by a battery. When the safety switch is closed and the igniter is connected to the terminals (usually a pair of alligator clips), electricity flows from the battery, through the LED and resistor (lighting the LED), through the igniter, through the switch, and back into the battery completing the circuit. Because the current must flow through the LED and resistor, it is greatly reduced - not enough to sufficiently heat the igniter and start the rocket engine. The resistor in this circuit is 300 Ohms - high enough to keep the igniter from heating up, but low enough to light the LED.
