Why can cheap LED lights cause eye strain that old incandescent bulbs didn't?
Show answer & explanation
Answer: Their light flickers too fast to notice
LEDs give off heat that dries out the eyes — LEDs run cool and send almost no heat toward your eyes, far less than an incandescent bulb. The strain comes from rapid, invisible flicker in cheaply made drivers.
Their light flickers too fast to notice ✓ — Cheap LED drivers switch the light on and off, or dim it with pulses, hundreds of times a second. You don't see the flicker, but your eyes and brain still respond to it, which can cause strain and headaches; old bulbs glowed steadily because a hot filament can't cool that fast.
LEDs give off ultraviolet rays that strain the eyes — Household white LEDs give off almost no ultraviolet light, less than sunlight through a window. The problem with cheap ones is flicker, not UV.
More Physics in Daily Life questions
- In a warm office that already reads 26 C, which change can make people feel cooler without lowering the thermostat?
- Why might 26 C feel acceptable in a breezy naturally ventilated summer building but too warm in a sealed winter office?
- On a warm, humid day, why can a 27 °C room feel worse once your skin is sweaty?
- Why can moving air make a 27 C room feel cooler without changing the thermometer?
- Why can a desk beside a cold window feel chilly even when the thermostat across the room still reads 22 C?
- In the same 22 C room, why might someone who just climbed stairs feel warm while someone sitting in a T-shirt feels chilly?