Lighting up the night
Before electric light, people lit homes with candles, oil lamps and gas lamps. These were dim, smoky and a fire risk. The electric light bulb made homes, streets and workplaces bright and safe at night, changing how people live and work.
Early electric light
| Year | Inventor | Development |
|---|---|---|
| 1802 | Humphry Davy (England) | Electric arc light between two carbon rods; very bright but impractical for homes |
| 1840s–1870s | Many inventors | Experiments with glowing wires in glass bulbs |
| 1874 | Henry Woodward and Mathew Evans (Toronto) | Patented a light bulb in Canada, then sold the patent to Thomas Edison |
| 1878–1880 | Joseph Swan (England) | Working carbon-filament bulbs; his house was the first lit by electric light |
| 1879–1880 | Thomas Edison (USA) | Long-lasting carbon-filament bulb; complete electric lighting system |
Edison didn’t invent the first light bulb, but his team made a practical, long-lasting one and built the power stations, wiring and meters needed to use it. In 1879, his carbonized cotton thread filament burned for about 14 hours; later carbonized bamboo filaments lasted over 1200 hours. Edison and Swan later combined their companies in Britain.
How incandescent bulbs work
An incandescent bulb makes light by heating.
- Electricity flows through a very thin wire called a filament.
- The filament resists the current and gets extremely hot, about 2500 °C.
- The hot filament glows, giving off light.
- The glass bulb is filled with an unreactive gas (like argon) or a vacuum so the filament doesn’t burn up.
In 1906–1910, tungsten filaments replaced carbon. Tungsten has the highest melting point of any metal (3422 °C), so bulbs could burn hotter and brighter.
The problem: about 90–95% of the energy becomes heat, not light. That’s why old bulbs got too hot to touch.
Better bulbs
| Type | How it works | Efficiency | Lifespan |
|---|---|---|---|
| Incandescent | Glowing hot filament | Low (about 5–10% light) | About 1000 hours |
| Halogen | Incandescent with halogen gas | Slightly better | 2000–4000 hours |
| Fluorescent lamp (tubes and CFLs) | Electricity excites mercury vapour, which gives off UV light; a coating glows | About 4 times better than incandescent | 8000–10 000 hours |
| LED | A semiconductor gives off light when current flows | Best: uses about 75–90% less energy than incandescent | 15 000–50 000 hours |
LEDs
LEDs (light-emitting diodes) produce light directly from electricity, with little wasted heat.
- Red LEDs were developed in 1962.
- Bright blue LEDs, invented in the early 1990s by Japanese scientists Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, made white LED lighting possible. They won the 2014 Nobel Prize in Physics.
- LEDs light homes, phone and TV screens, traffic lights, streetlights and car headlights.
Energy efficiency
Energy efficiency compares useful output (light) with energy used. Light output is measured in lumens; energy use in watts.
| Bulb type | Watts for about 800 lumens |
|---|---|
| Incandescent | 60 W |
| CFL | 13–15 W |
| LED | 8–10 W |
Canada and many other countries phased out most inefficient incandescent bulbs starting in 2014.
How electric light changed life
| Change | Effect |
|---|---|
| Longer usable days | People could work, read and study after dark |
| Safety | Fewer fires than candles and gas; brighter, safer streets |
| Industry | Factories could run night shifts |
| Cities | Streetlights, lit signs and nightlife |
| Electricity grids | The demand for lighting drove the building of power systems |
Light pollution
Too much artificial light at night causes light pollution. It hides the stars, confuses migrating birds and newly hatched sea turtles, and can disrupt human sleep. Canada has several Dark Sky Preserves, like Jasper National Park and Wood Buffalo National Park, where lighting is controlled so people can see the night sky.
Common mistakes
- Thinking Edison invented the light bulb from nothing. Many inventors contributed, including two Canadians.
- Thinking brighter means more watts. Watts measure energy use; lumens measure brightness.
- Throwing CFLs in the garbage. They contain mercury and should be recycled.
Try it yourself
- Feel (carefully) the heat near an incandescent bulb and an LED bulb after a few minutes. Which wastes more energy as heat?
- Read the packaging on bulbs at home. Compare lumens and watts.
- Count how many light bulbs are in your home and estimate how much energy you’d save switching all to LEDs.
Quick recap
- Many inventors developed the light bulb; Edison and Swan made practical versions around 1879–1880.
- Incandescent bulbs heat a tungsten filament until it glows, wasting most energy as heat.
- Fluorescent lamps and especially LEDs are much more efficient.
- Electric light extended the day and transformed industry and cities.
- Too much light causes light pollution.