Identify the metal having the lowest thermal conductivity.

Question

Question

This question was previously asked in

RRB ALP Electronics Mechanic 21 Jan 2019 Official Paper (Shift 3)

Answer 1

Concept:

Thermal Conductivity:

Thermal conductivity refers to the ability of a given material to conduct/transfer heat.
It is generally denoted by the symbol ‘k’ but can also be denoted by ‘λ’ and ‘κ’.
The reciprocal of this quantity is known as thermal resistivity.
Materials with high thermal conductivity are used in heat sinks whereas materials with low values of λ are used as thermal insulators.
The law of heat conduction states that the rate at which heat is transferred through a material is proportional to the negative of the temperature gradient and is also proportional to the area through which the heat flows.
The differential form of this law can be expressed through the following equation: q = - k ΔT, where k = thermal conductivity, ΔT = temperature gradient, q = heat flux

Explanation:

The thermal conductivity of the copper is 385.0 W/mK.
The thermal conductivity of mercury is 7.9 W/mK.
The thermal conductivity of Aluminium is 205 W/mK.
The thermal conductivity of Silver is 419 W/mK.
Hence, from the above data, the thermal conductivity of mercury is the lowest.