Electric lamp: principle of operation, device, advantages and disadvantages

Today it is difficult to imagine the life of people without an electric lamp. This rather simple device is used to illuminate various premises and streets. There are a large number of types of light bulbs that differ in luminescence power and principle of operation. Recently, more and more users are paying attention to energy-saving devices, but an ordinary incandescent lamp is in no hurry to give up positions.

Operating principle

The principle of operation of an incandescent lamp is quite simple.as well as the design of this device. The electric current passes through the refractory conductor and heats it up to a high temperature. It should be noted that the heating temperature depends on the voltage supplied to the device. According to Planck's law, a heated conductor is capable of generating electromagnetic waves.

The higher the temperature, the shorter the wavelength of the emitted radiation. Waves of the visible spectrum appear when the conductor is heated to several thousand degrees on the Kelvin scale. If the spiral of an electric bulb is heated to 5000 K, then it will glow with a neutral light (similar to what the sun emits). As the temperature decreases, the color of the glow will begin to change first to yellow and then to red.

In lamps, the predominant part of the energy is converted into heat and only a small amount of it is converted into a luminous flux. It should also be remembered that the human organs of vision are able to perceive only a certain range of light waves. To increase the illumination of the room, it is necessary to increase the temperature of the coil. However, this is possible only up to a certain index, which is limited by the properties of the conductor material.

Thus, the maximum bulb temperature is 3410 degrees on the Celsius scale. Further heating of the tungsten will deform and melt the material. However, even this temperature can only be reached under certain environmental conditions. If tungsten comes in contact with oxygen, then it turns into oxide. When air is pumped out of the bulb, it will be possible to create a lamp with a maximum power of 25 watts. More powerful devices contain inert gases in the flask.

Design features

Although lamps differ in design, they share three elements in common - leads, a conductor, and a glass bulb. Some special purpose devices may not have a plinth, as they use a different type of holder. Also, sometimes a ferronickel fuse is built into the bulbs. Most often, it is mounted in a leg, therefore, after the failure of the conductor, the flask does not collapse.

When the filament breaks, an electric arc is created, which melts the remaining material. The substance in the molten state falls on the glass container and can destroy its integrity. The fuse is able to prevent the spiral melting process. However, this technology has not become widespread due to low efficiency.

If we talk about what the light bulb consists of, then it is necessary to note the main structural elements. These include:

• a flask made of glass;
• radiating conductor;
• electrodes;
• base;
• gas environment;
• holders of the radiating conductor.

Flask and gas environment

Thanks to the glass container, the filament is protected from the oxidation process that occurs when the material of the emitting conductor interacts with oxygen. The first electric incandescent lamps were produced with a vacuum bulb. Now only low-power devices are produced using this technology. For the production of more powerful devices, a nitrogen-argon mixture or argon alone is most often used. Also, some bulbs may contain xenon or krypton. The thermal radiation of the filament material depends on the molar mass of the gas.

A separate group is halogen bulbs, into the glass container of which a gas of the halogen group is pumped. When heated, the material of the radiating conductor evaporates and reacts with these gases. The substance obtained during the chemical process is rapidly degraded under the influence of high temperature and returns to the filament. As a result, not only does the efficiency of the device increase, but also its service life increases.

Radiating conductor

The filament can be of any shape and depends on the specifics of the device. Most often, in an ordinary light bulb, the conductor has a round cross-section, but you can also find a ribbon one. It should be noted that even coal was used in the first lampscapable of heating up to a temperature of 3559 degrees Celsius. However, in modern devices, the main material of the filament is tungsten.

Also, this element can be made of an osmium-tungsten alloy. The choice of the type of spiral is not random, since its dimensions depend on it. Bispirals and even trispirals can be used in modern lamps. They are obtained by re-twisting. This allows you to increase the efficiency of the device due to a decrease in the heat release rate.

Lamp base

This element is standardized and has a specific shape and dimensions. As a result, it is easy to replace the light bulb after its failure.. Today, devices with an E14 base are most often used., E27, as well as E40. The decoding of this marking is extremely simple - the numbers after the letter E indicate the outer diameter of the element.

Since there are now a large number of types of lamps, some of them differ in the design of the base. For example, there are devices that are held in the chuck by friction. It should also be noted that the base in the incandescent lamp device performs the following functions:

• connects several elements;
• represents one of the contacts;
• allows you to securely mount the device in the holder.

Advantages and disadvantages

All technical devices have not only advantages, but also disadvantages. Incandescent bulbs are no exception.

Positive traits

One of the main advantages of these devices is the simplicity of the design, which makes the cost of the product low. Now you can easily purchase a device of the desired power and dimensions. An equally important advantage of classic light bulbs is the luminescence spectrum of their emitting element. Since it is as close as possible to sunlight, it cannot negatively affect the organs of vision.

A heated filament has thermal inertia, so the light it emits is virtually pulsation-free. This distinguishes conventional incandescent bulbs from other types of products (for example, fluorescent lamps). In the production of these devices, no harmful substances are used, so that special technologies are not required for their disposal.

Negative properties

One of the main disadvantages of the devices can be considered the dependence on the supply voltage indicator. If it increases and exceeds the permissible limits, then the spiral wears out quickly. When the voltage drops, the luminous flux emitted by the device also decreases.

In addition, it should be remembered that the emitting element is designed to operate over a long period of time. The resistance index of the cold spiral is significantly lower in comparison with the operating mode.

Because of this, at the moment of switching on, a strong surge in current occurs, which leads to the evaporation of the filament material. Thus, the service life of the device depends on the number of starts.

However, this disadvantage can be dealt with by using special soft starters - dimmers. Also, with their help, you can adjust the luminous flux index in a fairly wide range.

The most serious disadvantage of incandescent lamps is their low efficiency. Most of the electricity is converted into heat, which is dissipated in the environment. Nowadays, LED lamps are increasingly used to save on electricity.