Two resistors + load
Divide the invisible.
Two resistors turn 5 volts into a different voltage. What changes when you connect another component to the output?
- ADC · Analog-to-digital converter
- Analog-to-digital converter. Converts a measured analog voltage into a number a digital device can use. It is mentioned in the reading, not simulated here.
EXPERIMENT BENCH
Change the circuit settings, predict the readings, then check a challenge. These are learning models, with the assumptions explained in each lesson.
Sign in to save progress. Guest progress stays on this device.
A neighbour changes the rules.
Ideal 5 V source. The 1 kΩ load connects in parallel with the lower resistor. Tolerances and heating are omitted.
The divider has R₁ above and R₂ below. Unloaded: Vout = 5 × R₂ / (R₁ + R₂). With a load, replace R₂ with R₂ ∥ Rload. A divider is useful for signals, but usually unsuitable as a device power supply.
Difficulty
Build · Half the supply
With no load, power on and set the output to 2.5 V ±0.05 V.
Need a hint?
Equal resistances split the voltage in half.
Explore · An unexpected neighbour
With R₁ = R₂ = 1 kΩ, connect the load. Get about 1.67 V and find out why it dropped.
Need a hint?
1 kΩ in parallel with R₂ gives 500 Ω. Output: 5 × 500 / 1500.
Solve it · Bring the voltage back
Keep the load connected. Set the output between 2.4 and 2.6 V.
Need a hint?
Match R₁ to the equivalent lower resistance. Try R₂ = 1 kΩ and R₁ = 500 Ω.
Extra reading and circuit recipes
A voltage divider can be a sensor translator
Two resistors share the supply voltage. Their junction gives you a smaller voltage that can represent a measurement or set a reference. Replace one resistor with a sensor, and a physical change can become an electrical signal.
With no load at the output
Vout = Vs × R2 / (R1 + R2)
With two 1 kΩ resistors on 5 V, the output is 2.5 V. Add a 1 kΩ load across the lower resistor: the effective lower resistance is 500 Ω, so the output falls to about 1.67 V.
Same ratio, different cost
1 kΩ + 1 kΩ and 10 kΩ + 10 kΩ both give half the supply with no load. The larger pair draws one tenth of the current.
Measuring can change the answer
A load attached to the midpoint creates another current path. It acts in parallel with the lower resistor and pulls the output down.
A knob is a moving divider
A potentiometer has a resistive track and a wiper. Turning the shaft changes the two portions of the track, changing the wiper voltage.
A useful trap to avoid
A resistor divider is a signal circuit, not a general replacement for a power supply regulator. A changing load changes its output. An ADC input also needs suitable voltage limits and settling time.
A 1 kΩ load is added across the lower 1 kΩ resistor. The output…
- rises above 2.5 V
- stays at 2.5 V
- falls below 2.5 V
Read more
The effective lower resistance decreases. Its share of the supply voltage becomes smaller.
One-third reference
Generate about 1.67 V from 5 V with no load.
The lower resistor gets one third of the total voltage.
Rescue a loaded divider
Compensate for the fixed 1 kΩ load in this experiment.
The lower 1 kΩ and load 1 kΩ form 500 Ω. Matched with the upper 500 Ω, they restore 2.50 V.