Final answer:
Aluminum's higher coefficient of thermal expansion compared to copper can cause it to loosen from under terminal screws when heated, leading to potential safety hazards such as fires. Special care must be taken in making connections with aluminium in electrical applications.
Step-by-step explanation:
Aluminum has a higher coefficient of thermal expansion than copper. Due to this property, aluminium will expand more than copper when exposed to heat. This means that aluminium could loosen from under terminal screws as it expands more with temperature increases. In electrical applications, this is a concern because loose connections can lead to potential safety hazards, such as fire risks. Moreover, when heat is applied, not only does the bulk material expand, but any existing holes within the material also increase in size due to the overall expansion of the surrounding material. This can further exacerbate the loosening of connections in cases where aluminium is used in electromagnetic components.
Aluminium is chosen often over copper for certain applications because it is cheaper, even though it requires a larger diameter to match the resistance per length of copper wires. However, the physical properties of aluminium, like its lower ductility and tensile strength compared to copper, along with its higher rate of thermal expansion, means that special care must be taken when making connections. Moreover, the oxidation of aluminium, which does not conduct electricity, can compound these issues. Thus, special techniques are necessary when utilizing aluminium in wiring and ensuring proper connections, to prevent any possible fire hazard due to its tendency to loosen from terminal screws.