Question

What has the highest resistivity?

Answer 1

Hint : Resistivity is also known as specific resistance of a material. It can be defined as the magnitude of resistance of a specific conductor (material) of specific size (length and area of cross-section). Resistivity depends upon the nature (material) of the substance or conductor and the temperature at which it is measured.

Complete Step By Step Answer:
We know that resistance is a force which opposes the flow of current. So, resistivity is the specific resistance of a specific conductor (material) of specific size (length and area of cross-section). It is also known as electrical resistivity. It is denoted by a symbol $\rho$ which is known as “rho”. The SI unit of resistivity is “ohm-meter” which can also be written as $\Omega m$ .
Since, at constant temperature, resistivity differs in different materials such as metals which are good conductors and have low resistivity and the alloys have high resistivity values.
Nichrome has the highest resistivity of all the materials. Nichrome is an alloy of chromium, nickel and Iron. The composition of these metals are:
$Cr = 15\%$
$Ni = 60\%$
$Fe = 25\%$
Nichrome is also known as Brightray. It shows the heating effect of electric current because of the very high resistance which opposes the flow of electric current and hence, this opposition produces a lot of heat.
Therefore, Nichrome alloy has the highest resistivity of $1.10 \times {10^{ - 6}}\Omega m$ .

Note :
Nichrome has the highest resistivity and shows the heating effect of electric current because of its high resistance, it opposes the flow of current and hence, it produces a lot of heat. That is why it is used as a heating coil in many electrical appliances of the home such as room heaters, water heaters, ovens, heating rods, etc.