Pull-down Resistor Circuit Schematic
by AdamStanislav - uploaded on September 27, 2017, 12:36 am
If the switch S1 is closed, electricity takes the path of the least resistance and flows from the positive terminal Vin through the 100Ω resistor R1 to the Input pin. If the switch is open, the Input pin is connected to the ground through the two resistors R1 and R2, so no electricity is floating toward the Input pin, as it would without the 10kΩ pull-down resistor R2, at least for some time after the switch S1 was opened. This is important in digital electronics, where an input pin needs to be in just one of two states, high or low, at any moment in time.
This is a conceptual schematic. The switch does not have to be a physical switch, such as a button. It can be, and often is, a digital component that can switch between two states and let electricity through in one state, while blocking it in the other.