How to Make Incandescent Light Bulbs More Efficient

Unlike LEDs, incandescent bulbs emit light by sending electricity through a filament that heats up and glows. Researchers have discovered a way to make those filaments more efficient.

But it’s too late to save Edison’s bulb. Starting this month, the Department of Energy will start enforcing regulations to phase out most old-fashioned bulbs.

Origins

The incandescent light bulb is one of the wonders of our modern world. It’s used almost everywhere and is found in light fixtures, table lamps and desk lamps. It emits light when current passes through it, which is created when electrons move from higher levels to lower levels in the atoms it touches (called filling or emptying holes). When this occurs, excess energy is released as heat and glows.

English chemist Humphry Davy invented the first electric lamp in 1809. He connected two wires to a battery and attached charcoal strips between them, which glowed when current was passed through them. Davy received a patent for his invention but it never went into production due to the expense of platinum filaments used in the device.

In the early 1800s, Joseph Swan and Thomas Edison both worked on an incandescent light bulb. Edison’s version was a success and he received the US patent in 1879. One of the key reasons for this was a new pump that he developed called the Sprengel pump. This was a mercury-based pump that allowed for a much better vacuum in the bulb, which would prevent air from oxidizing and ruining the carbon filament.

After he got the patent, Edison began making his light bulbs in large numbers and promoting them at trade shows and expositions. He output speed sensor continued to improve his design until he was producing bulbs that lasted more than 1200 hours with a bamboo filament.

Basics

The standard incandescent light bulb has a threaded metal base (known as an Edison or screw base) that is connected to a fine filament of tungsten metal. The filament is coiled within a glass bulb that is evacuated or filled with inert gas to prevent oxidation and protect the filament from burning out. Electric current passes down a wire from the base to the filament and back down through the glass bulb to complete the circuit. The filament generates light when heated and emits heat when it cools. The amount of light emitted is measured in lumens.

Humphrey Davy developed the carbon arc lamp in 1809, and many inventors tried to perfect an incandescent light bulb before Edison. Edison’s first bulbs lasted only about fourteen hours, but his later designs lasted much longer.

A few years after the bulb became popular, Junichi Miura at Tokyo Electric created a double coiled filament that improved luminous efficacy. He also invented a silica coating to diffuse the light and reduce glare. These improvements gave consumers a more consistent, brighter light and increased the lifespan of incandescent light bulb the bulb by reducing uneven heating. Typically, an incandescent bulb will last for about 1000 hours, depending on its make and wattage. A bulb operated above its rated voltage will burn brighter, but it will have a shorter life span.

Energy Efficiency

Incandescent light bulbs are cheap to manufacture, operate on low voltages, work well with either alternating or direct current and are compatible with controls such as dimmers. They produce a soft, warm glow and are well-suited for decorative or task lighting. But they also waste a lot of energy – 95 percent of it is converted to heat instead of light. Because of this, countries are phasing out standard incandescent light bulbs and setting higher efficiency standards.

The tungsten filament in the bulb is heated by electricity to high temperatures, emitting infrared radiation and producing visible light (incandescence). That radiant energy travels through a glass envelope that’s partially evacuated or filled with inert gas to prevent the filament from burning out prematurely. The orientation of the filament also influences efficiency. A filament that’s oriented parallel to the glass reduces convective losses and increases luminous efficacy.

In contrast, LEDs – or light-emitting diodes – have no filament and convert electricity into visible light using an entirely different process. A LED has two electrodes, an anode and a cathode, with semi-conductive material in between. When an electrical current passes through the anode and cathode, the LED emits a bright, white light. These devices are becoming more and more popular for use in home lighting, as they consume less electricity than incandescents and offer the benefit of instant on/off switching.

Safety

The incandescent light bulb is one of the most widely used bulb types. It can be found in everything from the lamp at your bedside to the headlights in your car. They come in many different shapes and sizes and are available with clear or frosted glass.

The electric current passing through the filament heats it to a high temperature, and some of the heated metal is released as thermal radiation (light). The light that you see is produced by this process. The majority of the energy that passes through the filament is wasted as heat, but about 10% of it is converted to visible light.

Since incandescent bulbs run so hot, they should never be used in proximity to combustible materials or furnishings. They are also more fragile than other bulb types and can break suddenly. This can lead to dangerous shards of glass that will scatter all over the floor and end up in your hair, mouth, or eyes if you are not careful when changing a bulb.

The shards of glass that are produced by breaking an incandescent light bulb can be very sharp. These shards are not easily visible, but they can cut you if you try to handle the broken light bulb with bare hands. Be sure to use a pair of thick rubber gloves when touching a light bulb that has been turned off. Also, be careful not to twist the base of a light bulb too hard. If the base of a bulb is not secured properly, it can fall out of the socket and break.