Electrical Resistivity and Conductivity

A man covers his body with a blanket of thickness 4 mm. His temperature is 37°C and that of the atmosphere is 27°C. If the coefficient of thermal conductivity of wool is 1.2 × 10^-5 MKS units, heat lost by him per hour per square meter area is: 

Define the term 'conductivity' of a metallic wire. Write its SI unit.

Define the term 'electrical conductivity' of a metallic wire. Write its S.I. unit.

An electrolysis experiment is stopped and the battery terminals are reversed.

A heater coil is to be constructed with a nichrome wire (ρ = 1.0 × 10⁻⁶ Ωm) that can operate at 500 W when connected to a 250 V supply. (a) What would be the resistance of the coil? (b) If the cross-sectional area of the wire is 0.5 mm², what length of the wire will be needed? (c) If the radius of each turn is 4.0 mm, how many turns will be there in the coil?

Define current density. Write an expression which connects current density with drift speed