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Physics Question on Thermodynamics

At room temperature 27C, 27^\circ\text{C} , the resistance of a heating element is 50Ω50 \, \Omega. The temperature coefficient of the material is 2.4×1042.4 \times 10^{-4} C1^\circ\text{C}^{-1} . The temperature of the element, when its resistance is 62Ω62 \, \Omega , is _________C\degree C.

Answer

The relationship between resistance and temperature is given by:
R=R0(1+αΔT),R = R_0 \left( 1 + \alpha \Delta T \right),
where: \begin{itemize} \item R0=50ΩR_0 = 50 \, \Omega (resistance at room temperature), R=62ΩR = 62 \, \Omega (resistance at the higher temperature), \alpha = 2.4 \times 10^{-4} \degree{C}^{-1} (temperature coefficient), ΔT=TT0\Delta T = T - T_0 (change in temperature), T0=27CT_0 = 27^\circ \mathrm{C} (initial temperature).
Rearrange to solve for ΔT\Delta T:
ΔT=RR0αR0.\Delta T = \frac{R - R_0}{\alpha R_0}.

Substitute the given values:
ΔT=6250(2.4×104)50.\Delta T = \frac{62 - 50}{(2.4 \times 10^{-4}) \cdot 50}.

Simplify: ΔT=12(2.4×104)50=120.012=1000C.\Delta T = \frac{12}{(2.4 \times 10^{-4}) \cdot 50} = \frac{12}{0.012} = 1000^\circ \mathrm{C}.
The final temperature TT is: T=T0+ΔT=27+1000=1027C.T = T_0 + \Delta T = 27 + 1000 = 1027^\circ \mathrm{C}.

Explanation

Solution

The relationship between resistance and temperature is given by:
R=R0(1+αΔT),R = R_0 \left( 1 + \alpha \Delta T \right),
where: \begin{itemize} \item R0=50ΩR_0 = 50 \, \Omega (resistance at room temperature), R=62ΩR = 62 \, \Omega (resistance at the higher temperature), \alpha = 2.4 \times 10^{-4} \degree{C}^{-1} (temperature coefficient), ΔT=TT0\Delta T = T - T_0 (change in temperature), T0=27CT_0 = 27^\circ \mathrm{C} (initial temperature).
Rearrange to solve for ΔT\Delta T:
ΔT=RR0αR0.\Delta T = \frac{R - R_0}{\alpha R_0}.

Substitute the given values:
ΔT=6250(2.4×104)50.\Delta T = \frac{62 - 50}{(2.4 \times 10^{-4}) \cdot 50}.

Simplify: ΔT=12(2.4×104)50=120.012=1000C.\Delta T = \frac{12}{(2.4 \times 10^{-4}) \cdot 50} = \frac{12}{0.012} = 1000^\circ \mathrm{C}.
The final temperature TT is: T=T0+ΔT=27+1000=1027C.T = T_0 + \Delta T = 27 + 1000 = 1027^\circ \mathrm{C}.