The click of the switch - and the dark room instantly changed, the details of the smallest elements of the interior became visible. This is how energy from a small device instantly spreads, flooding everything around with light. What makes you create such a powerful radiation? The answer is hidden in the name of the lighting device, which is called an incandescent lamp.
The history of the creation of the first lighting elements
The origins of the first incandescent lamps date back to the beginning of the 19th century. Or rather, the lamp appeared a little later, but the effect of the glow of platinum and carbon rods under the influence of electrical energy has already been observed. Two difficult questions arose before scientists:
- finding high-resistance materials capable of heating up under the influence of current to a state of emission of light;
- Prevention of rapid combustion of the material in the air.
Research andinventions of the Russian scientist Alexander Nikolaevich Lodygin and the American Thomas Edison.
Lodygin suggested using carbon rods as an incandescent element, which were in a sealed flask. The disadvantage of the design was the difficulty of pumping out air, the remnants of which contributed to the rapid combustion of the rods. But still, his lamps burned for several hours, and developments and patents became the basis for creating more durable devices.
The American scientist Thomas Edison, having familiarized himself with the works of Lodygin, made an effective vacuum flask, in which he placed a carbon thread made of bamboo fiber. Edison also provided the lamp base with a threaded connection inherent in modern lamps, and invented many electrical elements, such as: a plug, a fuse, a rotary switch, and much more. The efficiency of the Edison incandescent lamp was small, although it could work up to 1000 hours of time and received practical use.
Subsequently, instead of carbon elements, it was proposed to use refractory metals. The tungsten filament used in modern incandescent lamps was also patented by Lodygin.
The device and the principle of operation of the lamp
The design of an incandescent lamp has not fundamentally changed for more than a hundred years. It includes:
- A hermetically sealed flask that limits the working space and is filled with an inert gas.
- The plinth that hasspiral shape. It serves to hold the lamp in the socket and electrically connect it to current-carrying parts.
- Conductors that conduct current from the base to the spiral and hold it.
- Incandescent spiral, the heating of which creates the emission of light energy.
When an electric current passes through a coil, it instantly heats up to the highest temperatures up to 2700 degrees. This is due to the fact that the spiral has a high current resistance and a lot of energy is spent to overcome this resistance, which is released as heat. Heat heats up the metal (tungsten), and it begins to emit photons of light. Due to the fact that the flask does not contain oxygen, tungsten does not oxidize during heating, and it does not burn out. An inert gas keeps hot metal particles from evaporating.
What is the efficiency of an incandescent lamp
Efficiency shows what percentage of the energy expended is converted into useful work, and what is not. In the case of an incandescent lamp, the efficiency is low, since only 5-10% of the energy goes to emit light, the rest is released as heat.
The efficiency of the first incandescent lamps, where the carbon rod acted as the filament, was even lower compared to modern devices. This is due to additional losses due to convection. Spiral filaments have a lower percentage of these losses.
The efficiency of an incandescent lamp directly depends on the heating temperature of the spiral. As a standard, a 60 W lamp coil heats up to 2700 ºС, atthis efficiency is only 5%. It is possible to increase the heating value to 3400 ºС by increasing the voltage, but this will reduce the life of the device by more than 90%, although the lamp will shine brighter and the efficiency will increase to 15%.
It is wrong to think that an increase in lamp power (100, 200, 300 W) leads to an increase in efficiency only because the brightness of the device has increased. The lamp began to shine brighter due to the greater power of the spiral itself, and as a result of greater light output. But energy costs have also increased. Therefore, the efficiency of a 100 W incandescent lamp will also be within 5-7%.
Varieties of incandescent lamps
Incandescent lamps come in various designs and functional purposes. They are divided into lighting fixtures:
- General use. These include lamps for domestic use of different power, designed for a mains voltage of 220 V.
- Decorative design. They have non-standard types of flasks in the form of candles, spheres and other shapes.
- Illumination type. Low power color-coated lamps for colorful illuminations.
- Local destination. Safe voltage devices up to 40 V. They are used on production tables, to illuminate the workplaces of machine tools.
- Mirror coated. Lamps that create directional light.
- Signal type. Used to work in the dashboards of various devices.
- For transport. A wide range of lamps of increased wear resistance and reliability. Features a user-friendly design for quick replacement.
- For spotlights. Lamps of increased power, reaching up to 10,000 W.
- For optical devices. Lamps for film projectors and similar devices.
- Commutator. Used as segments of the digital display of measuring instruments.
Positive and negative sides of filament lamps
Incandescent type lighting devices have their own characteristics. Positives include:
- instant ignition of the coil;
- environmental safety;
- small sizes;
- fair price;
- the ability to create devices of different power and operating voltage of both AC and DC;
- versatility of application.
To negative:
- low efficiency incandescent lamp;
- susceptibility to life-saving power surges;
- short working hours not exceeding 1000;
- fire hazard of lamps due to strong heating of the bulb;
- fragile design.
Other types of lighting fixtures
There are lighting lamps, the principle of which is fundamentally different from the operation of incandescent lamps. These include gas discharge and LED lamps.
There are a lot of arc or gas discharge lamps, but they are all based on the glow of gas when an arc occurs between the electrodes. The glow occurs in the ultraviolet spectrum, which is then converted into visible to the human eye.by passing through the phosphor coating.
The process that occurs in a gas discharge lamp includes two stages of work: the creation of an arc discharge and the maintenance of ionization and glow of the gas in the bulb. Therefore, all types of such lighting fixtures have a current control system. Fluorescent devices have a higher efficiency than incandescent lamps, but are unsafe because they contain mercury vapor.
LED lighting devices are the most modern systems. The efficiency of an incandescent lamp and an LED lamp is incomparable. In the latter, it reaches 90%. The principle of operation of the LED is based on the glow of a certain type of semiconductor under the influence of voltage.
What an incandescent bulb doesn't like
The life of an ordinary incandescent lamp will be shortened if:
- Voltage in the network is constantly overstated from the nominal one, for which the lighting device is designed. This is due to an increase in the operating temperature of the heating body and, as a result, increased evaporation of the metal alloy, leading to its failure. Although the efficiency of the incandescent lamp will be greater.
- Sharply shake the lamp during operation. When the metal is heated to a state close to melting, and the distance between the turns of the spiral is reduced due to the expansion of the substance, any mechanical, abrupt movement can lead to an inter-turn circuit imperceptible to the eye. This reduces the overall resistance of the spiral to current, contributes to its greater heating and rapidburnout.
- Water will get on the heated flask. A temperature difference occurs at the point of impact, which causes the glass to break.
- Touch your fingers on the bulb of the halogen lamp. A halogen lamp is a type of incandescent lamp, but has a significantly higher light and heat output. When touched, an invisible greasy stain from the finger remains on the flask. Under the influence of temperature, the fat burns, forming soot, which prevents heat transfer. As a result, at the point of contact, the glass begins to melt and may burst or swell, disrupting the gas regime inside, which leads to burnout of the spiral. Halogen incandescent lamps have higher efficiency than ordinary ones.
How to change the lamp
If the lamp is burned out, but the bulb has not collapsed, then you can replace it after it has completely cooled down. In this case, turn off the power. When screwing in the lamp, the eyes do not need to be directed in its direction, especially if it is not possible to turn off the electricity.
When the bulb burst, but retained its shape, it is advisable to take a cotton cloth, fold it in several layers and, wrapping it around the lamp, try to remove the glass. Next, using pliers with insulated handles, carefully unscrew the base and screw in a new lamp. All operations must be carried out with the power off.
Conclusion
Despite the fact that the efficiency of an incandescent lamp is a small percentage and it has more and more competitors, it is relevant in many areas of life. There is even the oldest light bulb, continuously working for more than a hundred years. Is this not a confirmation and perpetuation of the genius of the thought of a person striving to change the world?
