Q. 74.8( 24 Votes )
A silver wire has a resistance of 2.1 W at 27.5 °C, and a resistance of 2.7 W at 100 °C. Determine the temperature coefficient of resistivity of silver.
Resistance of silver wire at 27.5 °C R1 = 2.1 Ω
Resistance of silver wire at 100 ° C R2 = 2.7 Ω
Let temperature coefficient of silver wire is given by α.
The formula for α is: R2 = R1[1 + α(T2-T1)]
⇒ R2 - R1 = R1α(T2 - T1)
⇒ R2 - R1 = R1α (T2 - T1)
⇒ α = 0.0039°C
Temperature Coefficient of silver wire is 0.0039 per °C.
Rate this question :
Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables. (ρAl = 2.63 × 10–8 Ωm, ρCu = 1.72 × 10–8 Ωm, Relative density of Al = 2.7, of Cu = 8.9.)NCERT - Physics Part-I
(a) Define the term ‘conductivity’ of a metallic wire. Write its SI unit.
(b) Using the concept of free electrons in a conductor, derive the expression for the conductivity of a wire in terms of number density and relaxation time. Hence obtain the relation between current density and the applied electric field E.Physics - Board Papers
(a) Consider circuit in Fig 3.10. How much energy is absorbed by electrons from the initial state of no current (ignore thermal motion) to the state of drift velocity?
(b) Electrons give up energy at the rate of RI2 per second to the thermal energy. What time scale would one associate with energy in problem (a)? n = no of electron/volume = 1029/m3, length of circuit = 10 cm, cross-section = A = (1mm)2
Physics - Exemplar
Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1mm. Conductor B is a hollow tube of outer diameter 2mm and inner diameter 1mm. Find the ratio of resistance RA to RB.Physics - Exemplar
Temperature dependence of resistivity ρ(T) of semiconductors, insulators and metals is significantly based on the following factors:Physics - Exemplar
As the temperature of a conductor increases, its resistivity and conductivity change. The ratio of resistivity to conductivity.HC Verma - Concepts of Physics Part 2