Electric Circuit Simulator (2D)

Wiring

Source & Load

Battery voltage U 9.0 V

Resistance R 10 Ω

Circuit closed — current flowing.

Live Readout

Current I

0.90 A

Voltage U

9.0 V

Resistance R

10 Ω

Power P

8.1 W

How it works

Current only flows around a closed loop — open the switch and the loop breaks, so I drops to zero everywhere in that loop.

Ohm's law ties the three quantities together: I = U / R. Raise the battery voltage U and current rises in proportion; raise the resistance R and current falls in proportion. Power dissipated as heat and light in the resistor and bulb is P = I²R (equivalently P = U·I) — it grows with the square of the current, which is why the bulb brightens sharply as R drops.

In series wiring the resistor and bulb share one loop, so the same current flows through both and their resistances add: R_total = R + R_bulb. In parallel wiring each branch sees the full battery voltage independently, so the combined resistance is lower than either branch alone: 1/R_total = 1/R₁ + 1/R₂, which is why a parallel circuit at the same voltage draws more current overall.