Engineering, 24.03.2020 20:54 Adeenieweenie
A small bulb is rated at 7.5 W when operated at 125 V. The tungsten filament has a temperature coefficient of resistivity α = 0.0045/°C. When the filament is hot and glowing, its temperature is seven times room temperature (20 °C). What is the resistance of the filament (in ohms) at room temperature?
Answers: 1
![R = R_{ref}[1+ \alpha(T-T_{ref} )]](/tpl/images/0561/3689/8e91a.png)
= resistance of conductor at reference temperature (20 degrees C)
= Reference Temperature 
![R_{ref} =\frac{R}{[1+ \alpha(T-T_{ref} )]}](/tpl/images/0561/3689/04c06.png)
![R_{ref} =\frac{2083.333}{[1+0.0045(140-20 )]}= 1352.79\Omega](/tpl/images/0561/3689/63f6f.png)
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A small bulb is rated at 7.5 W when operated at 125 V. The tungsten filament has a temperature coeff...
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