What is the voltage divider principle and when is it used?

• A. Uses series resistors to produce a fraction of input voltage.
• B. Requires parallel connection to drop voltage.
• C. Gives the same voltage across all components.
• D. Only applies to AC circuits.

Answer: (A)

A voltage divider uses resistors in series across a source to produce a fraction of the input voltage at the output node. For the simplest two-resistor divider, the voltage across the bottom resistor is Vout = Vin × (R2 / (R1 + R2)). By picking different resistor values, you set the exact fraction you need.

This setup is used whenever you need to scale a higher voltage down to a safer or usable level for a circuit, such as feeding an ADC input, biasing a transistor, or creating a reference voltage. It’s a passive method, so it’s simple and low-cost, but the output voltage depends on the load. If you connect a load that draws appreciable current, it forms a parallel path with the divider and shifts the fraction, so the load should be high impedance relative to the divider (or the design must account for it). The divider works for DC and steady-state signals, and the same idea applies to AC as long as you consider impedance and frequency effects.