Explanation:
Resistance is defined as the ability of a substance to resist the flow of current through the substance. Formula to calculate resistance is as follows.
R = [tex]\frac{\rho l}{A}[/tex]
As outer surface of a wire is in the shape of sphere. therefore, its area will be as follows.
A = [tex]4 \pi r^{2}[/tex]
or, A = [tex]4 \pi (\frac{d}{2})^{2}[/tex]
where, d = diameter of the sphere
This means that with increase in diameter of a conductor there will occur an increase in area of the wire. As area is inversely proportional to resistance so, increase in area will lead to a decrease in resistance.
On the other hand, relation between resistivity and temperature is as follows.
[tex]\rho \propto \frac{1}{d} \propto A^{2} \propto T[/tex]
where, [tex]\rho[/tex] = resistivity
d = mean free path of electrons
A = amplitude of atomic vibrations
T = temperature
Also, resistivity is directly proportional to resistance. So, with increase in temperature there will occur an increase in resistance of the conductor.
Thus, we can conclude that only technician B is correct.
