According to Ohm’s law, the potential difference across ends of conductor is directly proportional to the current through the it if its physical conditions are same. Then we can write,
V α I → V = IR
Here ‘R’ is constant known as resistance.
The reciprocal of resistance is known as Conductance.
Hence the formula for conductance can be given as,
As per the formula, we get the SI unit of conductance is 1/Ω or mho or Siemens.
Conductance of material depends upon the number of valance electrons present in a atom of material, nature of material, temperature etc.
Conductance of material decreases with temperature as its resistance rises due to rise in temperature.
The reciprocal of resistivity is known as conductivity. The formula for the conductivity is given as,
SI unit of conductivity is Siemen/meter.
Q.1) Conductance of wire having resistance of 10 kΩ will be….
a) 10-4 siemen
b) 10-3 siemen
c) 10-2 siemen
d) none of these
Q.2) The conductance of material…….
a) decreases with increase in temperature
b) increases with increase in temperature
b) remains same with rise in temperature
d) either ‘a’ or ‘b’
Q.3) The conductance of conductor will gets…….if its resistance is doubled.
b) remains same
Q.4) SI unit of conductivity is…
Q.5) The resistivity of material of wire is 2.3×10-3Ω-m, conductivity will be…..
a) 3×103 S/m
b) 3×102 S/m
c) 3 S/m
d) 43×102 S/m
Q.6) The length of conductor is doubled and area of material of conductor is halved, the conductivity of conductor will be……..
Q.7) The length and area of material of conductor are halved, the conductivity of conductor will be……
Q.8) The ratio of conductivity of conductors of resistivities in ratio 2:1 will be…
Q.9) Resistance of silver wire of cross-section area 0.02 mm2, length 2 m and conductivity of 6.30×10 7 S/m is…..
a) 1.2 Ω
b) 1.4 Ω
c) 1.6 Ω
d) 1.8 Ω
Q.2) a) decreases with increase in temperature
Q.3) c) halved
Q.4) a) Siemen/m
Q.5) b) 4.3×102 S/m
Q.6) d) unchanged
Q.7) c) (1/4)C
Q.8) a) 1:2
Q.9) c) 1.6 Ω