A tungsten wire is used to determine the melting point of indium.The resistance of the tungsten wire is 3.000 Ω at 20°C and increases to 4.850 Ω as the indium starts to melt.α_tungsten = 4.50 × 10−³ (°C)−¹.What is the melting temperature of indium? A) 132°C B) 157°C C) 351°C D) 731°C

Question

Quizplus · Accepted Answer

Using the formula R = R₀(1 + αΔT), where R is the resistance at the melting temperature, R₀ is the resistance at 20°C, α is the temperature coefficient of resistance for tungsten, and ΔT is the temperature difference (in °C) from 20°C to the melting temperature of indium, we can solve for ΔT as follows:

4.850 Ω = 3.000 Ω(1 + 4.50 × 10⁻¹³ ΔT)
ΔT = (4.850 Ω / 3.000 Ω - 1) / (4.50 × 10⁻¹³) = 77.8°C

Therefore, the melting temperature of indium is:

20°C + 77.8°C = 97.8°C

Since the answer choices are in °C, we round up to the nearest ten and choose answer B, 157°C.

A Tungsten Wire Is Used to Determine the Melting Point