Question

the resistance of a carbon filament at 0°c is 104 ohm. what should be the resistance of an iron filament which should be connected in series with the carbon filament so that the resistance of the combined filament does not change with temperature? the temperature coefficient of resistance of iron is àlpha=+0.0052°C-1 and of carbon is 0.0003°C-1

Answer 1

Answer:

Explanation:

=> The resistance of a carbon filament at 0°c is 104 ohm.

$R_{C}$= 104 ohm.

=> the temperature coefficient of resistance of iron is +0.0052°C and of carbon is -0.0003°C

$\alpha _{I}$ = +0.0052 °C

$\alpha _{C}$ = -0.0003 °C

=> The resistance of an iron filament which should be connected in series with the carbon filament so that the resistance of the combined filament does not change with temperature can be calculated as below:

Resistance of the iron at zero temperature*  temperature coefficient of iron + Resistance of the carbon at zero temperature*  temperature coefficient of carbon = 0

$R_{I} \alpha _{I} +R_{C} \alpha _{C} = 0$

[tex]R_{I} =\frac{-104*0.0003}{0.0052} = 6 ohm