Page 52 - Basic Electrical Engineering

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Example 1.10 A resistance element of cross-sectional area of 10 mm and
length 10 m draws a current of 4 A at 220 V supply at 20°C. Calculate the
resistivity of the material. What current will be drawn when the temperature

rises to 60°C? Assume α = 0.0003/°C.
20

Solution:

=10 mm 2

−6
=10 × 10 m 2
V= IR

or,

resistance, we call as R 20

or,

or,

−6
ρ = 55 × 10 ohm-m
60

given

ρ = 0.0003 /°C
20