LED Versus Incandescent: Why Modern Flashlights Use LEDs

Old torches used tiny glass bulbs with a glowing wire. Almost every modern torch, and every phone flash, uses an LED. Here's why.

How they work

• Incandescent bulbs pass electricity through a thin filament, which heats up and glows. Much of the energy is lost as heat.
• LEDs (light-emitting diodes) produce light when current passes through a semiconductor. Far more of the energy becomes light.

Comparison

Feature	Incandescent	LED
Efficiency	low, mostly heat	much higher
Battery life	short	far longer for the same light
Lifespan	limited; filaments burn out	very long
Durability	fragile glass and filament	solid-state, tougher
Size	bulky	tiny
Warm-up	instant	instant

Why it matters for torches

• Longer runtimes: an LED torch can run far longer on the same batteries.
• Toughness: with no filament to snap, LEDs cope better with drops.
• Small size: it's why a tiny light fits inside a phone.

Phone flash LEDs

A phone flash is a small LED beside the camera lens. Some phones have one, and some have two in different tones. The same LED provides light for the flashlight function when an app switches it on continuously.

Heat

LEDs make less heat than old bulbs but aren't heat-free. Under continuous use, the phone can warm near the flash. See our article on why phone torches get warm.

Colour of the light

Old bulbs gave a yellowish light. LEDs come in different colour temperatures, from warm to cool white. Phones usually use a fairly white or slightly cool LED.

What this means for you

If you use your phone torch briefly, the LED's efficiency means minimal battery impact. For long jobs, a dedicated LED torch will last longer than a phone.

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