The resistance of tungsten filament at 150°C is 133 Ω. What will be its resistance at 500°C? The temperature coefficient of resistance of tungsten is 0.0045 per °C.
A tungsten filament is a thin wire made of tungsten metal used in light bulbs and other electrical devices. Tungsten has a high melting point and excellent conductivity, making it ideal for producing light when heated. It can withstand high temperatures without melting, ensuring efficient performance in incandescent bulbs.
Class 11 Physics Chapter 10 Thermal Properties of Matter explores topics such as temperature and heat expansion of solids liquids and gases specific heat capacity latent heat and thermal conductivity. It covers thermal equilibrium and the laws of thermodynamics. The chapter also explains heat transfer methods like conduction convection and radiation and the behavior of matter under varying temperatures.
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To calculate the resistance of tungsten at 500°C, we make use of the formula for temperature-sensitive resistance:
Rₜ = R₀ × [1 + α × (Tₜ – T₀)]
Here,
– R₀ = 133 Ω (resistance at T₀ = 150°C),
– α = 0.0045 per °C (temperature coefficient),
– Tₜ = 500°C.
Now, substituting the values,
Rₜ = 133 × [1 + 0.0045 × (500 – 150)]
Rₜ = 133 × [1 + 0.0045 × 350]
Rₜ = 133 × [1 + 1.575]
Rₜ = 133 × 2.575 = 342.48 Ω.
The resistance is about 366 Ω.
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