Page 37 - Basic Electrical Engineering

state of zero resistance. The material at that state becomes superconducting,
i.e., conducting with no resistance at all.
Now suppose a conductor is heated from temperature t to t . The
2
1
resistance of the conductor at t is R and at t is R as has been shown in Fig.
2
2
1
1
1.2 (b).
Using eq. (1.5),

R = R (1 + α t)
0
0
t
or,

or,

Using eq. (1.5), we can write

R = R (1 + α 1)
0
0
1
and R = R (1 + α 2)
0
2
0

From fig 1.2 (b) using the relation in (1.6), we can write

or, α R (t − t ) = R − R 1
2
1
2
1 1
or, R = R + α R (t − t )
1
2
1 1
1
2
or, R = R [1 + α (t − t )] (1.7)
2
1
1 2
1

Thus, if resistance at any temperature t is known, the resistance at t 2
1
temperature can be calculated.