Question

Сопротивление угольного стержня уменьшилось от 5,0 до 4,5 Ом при повышении температуры от 50 до 545 `С. Каков температурный коэффициент сопротивления угля? На что указывает знак минус в ответе? ПОМОГИТЕ, ПЛИЗ, СЕССИЮ СДАЮ, СРОЧНО ПОМОЩЬ НУЖНА

Answer 1

Решение: α = (R1-R2)/R1(t2-t1)=0,5 Ом/5 ом * 495 оС = = -0,0002 Ом/оС   Ответ: α = -0,0002 Ом/оС Отрицательный коэффициент показывает, что уголь полупроводник, ибо полупроводники обладают отрицательным температурным коэффициентом  

Answer 2

Calculation of the Temperature Coefficient of Resistance

To calculate the temperature coefficient of resistance for the carbon rod, we can use the formula:

Temperature Coefficient of Resistance (α) = (ΔR / R₀) / ΔT

Where: - ΔR is the change in resistance (R₂ - R₁) - R₀ is the initial resistance - ΔT is the change in temperature (T₂ - T₁)

Given the following information: - Initial resistance (R₁) = 5.0 Ω - Final resistance (R₂) = 4.5 Ω - Initial temperature (T₁) = 50 °C - Final temperature (T₂) = 545 °C

Let's calculate the temperature coefficient of resistance using the provided values:

Step 1: Calculate the change in resistance (ΔR): ΔR = R₂ - R₁ = 4.5 Ω - 5.0 Ω = -0.5 Ω

Step 2: Calculate the change in temperature (ΔT): ΔT = T₂ - T₁ = 545 °C - 50 °C = 495 °C

Step 3: Calculate the temperature coefficient of resistance (α): α = (ΔR / R₀) / ΔT = (-0.5 Ω / 5.0 Ω) / 495 °C

Now, let's calculate the value of α:

α = (-0.5 Ω / 5.0 Ω) / 495 °C ≈ -0.00202 °C⁻¹

Interpretation of the Negative Sign

The negative sign in the answer indicates that the resistance of the carbon rod decreases as the temperature increases. This means that the carbon rod has a negative temperature coefficient of resistance. In other words, as the temperature rises, the resistance of the carbon rod decreases.

This behavior is typical for some materials, including carbon. As the temperature increases, the atoms in the material vibrate more vigorously, which leads to an increase in the number of charge carriers and a decrease in resistance.

I hope this helps! Let me know if you have any further questions.