what 2 properties of carbon make it a good material to use for motor brushes?
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Carbon is often used in motor brushes because of its two key properties: conductivity and durability.
1. Conductivity: One reason carbon makes a good material for motor brushes is its high electrical conductivity. Motor brushes are responsible for transferring electrical current from the power source to the armature (rotating part) of the motor. Carbon, as a conductive material, allows for efficient transfer of current. It has a high electron mobility, meaning that it readily allows the flow of electrons. This property ensures that the electrical energy is efficiently transmitted, minimizing energy loss and promoting better motor performance.
2. Durability: Carbon is also valued for its durability and resistance to wear. Motor brushes are in constant contact with the commutator, which is a rotating part of the motor that transfers electrical power to the armature. During operation, the brushes experience friction and wear due to the mechanical and electrical forces involved. Carbon's high durability and low friction coefficient enable it to withstand these conditions without deteriorating rapidly. It has a self-lubricating property, which helps reduce friction and extend the lifespan of the brushes. Moreover, carbon has excellent thermal stability, allowing it to resist heat and maintain its properties over a wide range of temperatures.
To recap, carbon's high electrical conductivity and durability make it an ideal material for motor brushes, ensuring efficient current transfer and longevity in demanding operating conditions.