Question

почему нити накала электрических лампочек нельзя изготавлевать из меди, а электрические провода, подводящие к ним ток,-из вольфрама?

Answer 1

вольфрам тугоплавый, и обладает высоким сопротивлением, и сильно грелся бы при использовании в качестве провода, а медь в лампочке расплавилась бы...!!!

Answer 2

Why can't the filaments of incandescent light bulbs be made of copper, while the electrical wires that supply them with current are made of tungsten?

The filaments of incandescent light bulbs are typically made of tungsten, not copper, due to several reasons:

1. Melting Point: Tungsten has a much higher melting point than copper. The high temperatures generated by the electric current passing through the filament would cause a copper filament to melt quickly, rendering the light bulb useless. Tungsten, on the other hand, has a very high melting point, making it suitable for use in incandescent light bulbs.

2. Resistance to Heat: Tungsten has excellent heat resistance properties. When an electric current passes through the filament, it heats up due to the resistance of the material. Tungsten can withstand the high temperatures generated by the electric current without deforming or melting, allowing the filament to emit light efficiently. Copper, on the other hand, has lower heat resistance and would not be able to withstand the high temperatures required for incandescent lighting.

3. Longevity: Tungsten filaments have a longer lifespan compared to copper filaments. The high melting point and heat resistance of tungsten allow the filament to last longer, resulting in a longer-lasting light bulb. Copper filaments would burn out quickly due to the high temperatures, leading to frequent bulb replacements.

4. Efficiency: Tungsten filaments have a higher efficiency in converting electrical energy into light compared to copper filaments. Tungsten has a higher emissivity, meaning it emits more light for a given amount of electrical energy. This makes tungsten a more suitable material for incandescent light bulbs, where the goal is to produce as much light as possible from the electrical energy supplied.

In contrast, electrical wires that supply current to the light bulbs are typically made of copper due to its excellent electrical conductivity. Copper is a highly conductive material that allows the efficient flow of electricity. It is also more cost-effective compared to tungsten, making it a preferred choice for electrical wiring.

In summary, the choice of tungsten for the filaments of incandescent light bulbs is due to its high melting point, heat resistance, longevity, and efficiency in converting electrical energy into light. Copper, on the other hand, is used for electrical wires due to its excellent electrical conductivity and cost-effectiveness.