LED vs Incandescent Bulb
LEDs convert far more input power to light and far less to heat.
How each one makes light
An incandescent bulb passes current through a thin tungsten filament until it is white hot. Most of the energy leaves as heat rather than light. An LED creates light directly in a semiconductor junction, so much more of the input energy becomes visible light.
Side by side
- Efficiency: a typical incandescent gives roughly 10 to 17 lumens per watt. Many household LEDs give 80 to 150 or more.
- Lifespan: incandescent bulbs commonly last around 1,000 hours. Quality LEDs are often rated for 25,000 hours or more.
- Heat: a filament bulb is too hot to touch. LED lamps are warm but release their heat through a heat sink instead of the beam.
- Durability: a glass filament breaks when knocked. A solid-state LED tolerates vibration well.
- Switching: LEDs reach full brightness immediately and are not harmed by frequent switching.
Where incandescent still has a point
Filament lamps give a smooth, continuous spectrum and a familiar warm glow, and they dim without extra electronics. Modern warm-white LEDs imitate that look well, but dimming them needs a compatible dimmer or driver.
Running cost example
A 60 W filament bulb and a 9 W LED lamp with similar brightness differ by 51 W. Over 1,000 hours that is 51 kWh of electricity saved by one lamp, before counting the cost of replacing bulbs.
Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.