Tungsten, or Wolfram (W), is a dense, silvery-white element with the atomic number 74, found in Group 6 of the periodic table. It is classified as a refractory metal, meaning it is highly resistant to heat and wear. As a metal, tungsten is electrically conductive, readily allowing the flow of electric current. The efficiency of current movement, however, varies significantly between different metals.
How Electricity Moves Through Metals
Electrical conductivity in metals is explained by the “sea of electrons” model. This model describes metallic solids as a lattice of fixed, positively charged ions surrounded by a cloud of delocalized valence electrons, which are free to roam throughout the crystal structure.
When a voltage is applied, it creates an electric field that pushes these free-moving electrons. The resulting coordinated drift of the delocalized electron cloud transfers charge, defining the electric current.
The ease with which these electrons move determines how well a material conducts electricity. Metals like silver and copper have a highly mobile electron sea, making them excellent conductors.
Tungsten’s Specific Electrical Characteristics
While tungsten is a conductor, it has a relatively high electrical resistivity compared to metals like silver or copper. Tungsten’s resistivity measures approximately 5.5 x 10^-8 ohm meters at 20 degrees Celsius.
This higher resistance causes a greater amount of electrical energy to be converted into heat when current passes through the wire. This effect is pronounced in materials with higher resistivity.
Tungsten possesses the highest melting point of all known metals, reaching an extreme of 3422 degrees Celsius. This allows the metal to become intensely hot due to its resistance without physically melting or losing structural integrity. The combination of moderate conductivity, high resistance, and extreme heat tolerance defines its utility in high-temperature electrical applications.
Industrial Uses Based on Conductivity
Tungsten’s high electrical resistance, coupled with its highest melting point, enables its most famous application: the incandescent light bulb filament. The thin tungsten wire heats up to over 2000 degrees Celsius, causing it to glow white-hot and emit visible light while remaining structurally intact.
Tungsten’s conductive stability at high temperatures is vital for high-duty electrical contacts and electrodes. In applications like Gas Tungsten Arc Welding (GTAW), the electrode must conduct high currents to create a stable, intense arc without degrading from the extreme heat. Alloys of tungsten are often used in circuit breakers and switches for reliable operation under high current and arcing conditions.
The metal is also essential in X-ray tubes, where a tungsten target is bombarded with electrons to generate X-rays. The target must efficiently conduct the current while withstanding the tremendous heat generated by the electron beam.