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Ohm’s law: the battery pushes, the resistor decides how much flows

Turn the battery knob or drag the resistor. Watch the charges speed up or slow down, the ammeter and voltmeter follow, and the resistor warm up. Everything here is an ideal, textbook component.

01 — One loop: battery → ammeter → resistor → back

1Ideal batteryFixed V, zero internal resistance

2Ideal ammeterIn series, 0 Ω, reads I

3Ideal voltmeterAcross R, infinite Ω, no current

4Resistor ROhmic, constant, always > 0 Ω

5Ideal wiresZero resistance, no drop

Voltage Vvoltmeter across the resistor

Current I = V ÷ R

Resistance Rcolour bands show its value

Power P = V × I

Battery voltage V V

0 V12 V

Resistance R Ω

1 Ω (R > 0 always)1000 Ω

Try:Does I double? Does P?

The numbers, with units

Ohm’s law

Electrical power

Cross-check

Units: 1 V ÷ 1 Ω = 1 A, and 1 V × 1 A = 1 W (1 joule per second).

I–V graph of this resistor

A resistor gives a straight line through zero. Drag the dot along it (or the battery knob) to change V; change R to tilt the line. The vertical scale rescales. The red area is V × I = power.

Drag the glowing hints on the picture, or use the sliders.Ideal model · not to scale

Same push, less flow

The voltmeter shows the battery’s push across the resistor. A larger R lets less current through for the same V, so the charges slow down, the ammeter drops, and the I–V line tilts flatter. Doubling V doubles I along the same line.

Where the power goes

Every charge loses energy in the resistor, and it leaves as heat at P = V × I. Doubling V doubles both V and I, so P quadruples. The glow is a visual scale of P, not a temperature rating. Real batteries, meters and wires have small resistances; here they are ideal.