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Which of the following materials are not used for the transmission and distribution of electrical power?
Copper
Aluminium
Tungsten
Steel
Tungsten
Tungsten is not used for transmission and distribution lines because it has very high resistivity compared to Aluminium or Copper, which leads to significant I2R power losses. Additionally, tungsten is extremely brittle and difficult to manufacture into long, flexible conductors suitable for overhead lines.
Tungsten is not used for transmission and distribution lines because it has very high resistivity compared to Aluminium or Copper, which leads to significant I2R power losses. Additionally, tungsten is extremely brittle and difficult to manufacture into long, flexible conductors suitable for overhead lines.
R=╧БALтАЛ тАФ Relation between resistance, resistivity, length, and area
PlossтАЛ=I2R тАФ Power loss due to conductor resistance
Transmission conductors must have high electrical conductivity (low resistivity ╧Б), high mechanical tensile strength to withstand environmental stress, and flexibility. Materials like ACSR (Aluminium Conductor Steel Reinforced) combine Aluminium for conductivity and Steel for mechanical support. Tungsten is suited for high-temperature filaments (due to its high melting point of 3422┬░C) but is unsuitable for large-scale power flow.
Aluminium is preferred for long-distance lines due to its light weight and low cost per unit conductance.
Copper has superior conductivity but is more expensive and denser.
Steel provides mechanical reinforcement in ACSR conductors.
Tungsten is a refractory metal used primarily in incandescent lamps.
Aluminium: Lightweight, cheap, and abundant.
Copper: Excellent conductivity and ductility.
Tungsten: High resistivity, extremely brittle, very expensive to draw into wire.
Copper: High cost and higher density than aluminium.
Aluminium: Overhead transmission and distribution.
Copper: Electrical wiring in homes, motor windings, and busbars.
Standard conductivity of Copper is approximately 58 MS/m, while Aluminium is approximately 35 MS/m.
Option C (Tungsten) is the correct answer as it is functionally and economically inefficient for power grid usage.
C is correct тАФ Tungsten is not used for transmission lines due to its high electrical resistance and brittleness.
When choosing transmission materials, remember the trade-off between conductivity (sigma) and mass-density; this is why Aluminium is almost always preferred over Copper for long-distance overhead transmission despite Copper's better conductivity.