*Resistivities and Temperature Co-efficients
Material: Re.in Ω-m at20° C : T.C at20°
Copper :- 1.59 × 10–8 : 0.00428
Aluminium :- 2.8 × 10–8. :0.0020
Silver :- 1.52 × 10–8 : 0.00377
Platinum :- 11 × 10–8 :0.00340
Iron :- (9 to 15) × 10–8 :0.0070
Mercury :- 19.9 × 10–8 :0.00089
German silver :- (4 Cu ; 2Ni ; 1 Zn) 20.2 × 10–8 :0.00027
Constantan or Eureka :- 49 × 10–8 – 0.00004 to :+ 0.00001
Carbon :- 7000 × 10–8 : – 0.0005
*IMPOTRTANT TERMS RELATING NETWORK AND DEFINATIONS:
1. Circuit. A conducting path through which an electric current either flows or is intended
to flow is called a circuit. The various elements of an electric circuit are called parameters (e.g.
resistance, inductance and capacitance). These parameters may be distributed or lumped.
2. Linear circuit. The circuit whose parameters are constant (i.e., they do not change with
voltage or current) is called a linear circuit.
3. Non-linear circuit. The circuit whose parameters change with voltage or current is called
a non-linear circuit.
4. Unilateral circuit. A unilateral circuit is one whose properties or characteristics change
with the direction of its operation (e.g. diode rectifier)
5. Bilateral circuit. It is that circuit whose properties or characteristics are same in either
direction (e.g. transmission line)
6. Electric network. An electric network arises when a number of parameters or electric
elements coexist or combine in any manner or arrangement.
7. Active network. An active network is one which contains one or more than one sources
of e.m.f.
8. Passive network. A passive network is one which does not contain any source of e.m.f.
9. Node. A node is a junction in a circuit where two or more circuit elements are connected
together.
10. Branch. The part of a network which lies between twto junctions is called branch.
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