Question 1

What is a voltage divider?

Accepted Answer

A voltage divider is a simple linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). It is usually created by connecting two resistors (R1 and R2) in series across a voltage source.

Question 2

What is the formula for calculating Vout?

Accepted Answer

The formula is Vout = Vin × (R2 / (R1 + R2)). It is derived directly from Ohm's Law and Kirchhoff's Voltage Law.

Question 3

Can I use a voltage divider as a power supply?

Accepted Answer

No, this is highly discouraged. Voltage dividers are only suitable for providing a reference voltage to high-impedance inputs (like an Arduino analog pin or an op-amp). If you connect a heavy load across R2, the load's resistance will run in parallel with R2, fundamentally changing your Vout calculation and causing the voltage to drop significantly.

Question 4

Why does the resistor's actual value matter if only the ratio matters?

Accepted Answer

While the ratio (R2 / Rtotal) determines the output voltage, the absolute values of the resistors determine how much current flows continuously from your battery or power supply straight to ground. If you use 1Ω and 2Ω resistors for a 12V battery, you will draw 4 Amps of current and likely set the resistors on fire. If you use 1MΩ and 2MΩ, you will draw practically no current, but the signal will be very weak.

Question 5

What is a good rule of thumb for selecting resistor values?

Accepted Answer

Usually, values in the 10kΩ to 100kΩ range are a safe bet for modern microcontroller logic (like scaling a 5V sensor down to a 3.3V Raspberry Pi input). It offers a good balance between minimizing power waste and providing a strong enough signal to overcome electrical noise.

Voltage Divider Calculator

Warning on Loads

4Volts

Circuit Characteristics

How the Divider Works

The Top Resistor (R1)

The Ground Resistor (R2)

Frequently Asked Questions

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