Question

1.
An aluminium conductor, having resistance of
15 2 at 40°C, is heated to 120'C If the RTC at
0°C is 0.00333/'C its RTC at 40°C will be
°C.​

Answer 1

answers

0.0029

Explanation:

The value of temperature coefficient is not constant, it depends on the initial temperature on which the increment of resistance is based

When the increment is based on an initial temperature of 0°C, the value of this coefficient is α0; Which is nothing but the reciprocal of the respective inferred zero resistance temperature of the substance

At any other temperature, temperature coefficient of electrical resistance is not same as this α0

Actually, for any material, the value of this coefficient is maximum at 0°C temperature

Say the value of this coefficient of any material at any t° C is αt, then its value can be determined by the following equation,

\({{\alpha }_{t}}=\frac{1}{t+\frac{1}{{{\alpha }_{0}}}}\)

Calculation:

Given α0 = 0.00333 /°C

t = 40°C

\({{\alpha }_{t}}=\frac{1}{40+\frac{1}{0.00333}}=0.0029/{}^\circ ~C~\)