Current
Understanding the Analogy Between Heat Flow and Electricity Flow
In engineering, it is often helpful to draw analogies between different physical systems to better understand or model them. A common analogy is made between the flow of heat in a thermal circuit and the flow of electricity in an electrical circuit. This thermal-electrical analogy allows engineers to use electrical circuit principles to solve heat transfer problems.
Let's examine the key quantities in both systems and their corresponding analogies:
| Thermal Circuit Quantity | Electrical Circuit Quantity |
|---|---|
| Heat Flow Rate (Q) | Electric Current (I) |
| Temperature Difference ($\Delta T$) | Voltage Difference ($\Delta V$) |
| Thermal Resistance ($R_{th}$) | Electrical Resistance ($R_{elec}$) |
Based on this analogy:
- The rate at which heat flows from a high temperature region to a low temperature region is analogous to the rate at which electric charge flows through a conductor, which is the electric current.
- The difference in temperature driving the heat flow is analogous to the difference in electric potential (voltage) driving the current flow.
- The resistance to heat flow is analogous to the resistance to electric current flow.
Therefore, when an analogy is drawn between heat flow and electricity flow in circuits, the heat flow of thermal circuits is equated in the electrical circuit against electric current.
Let's look at the options provided:
- Voltage: Voltage is analogous to temperature difference, not heat flow rate.
- Current: Current is analogous to heat flow rate.
- Resistance: Resistance (thermal or electrical) opposes the flow (heat or current), it is not the flow itself.
- Charge (coulombs): Charge is the quantity that flows over time to constitute current. It is not the rate of flow like heat flow rate.
Thus, the correct electrical quantity analogous to heat flow is current.
Important Questions from Fourier Law and Thermal Conductivity
Unit of thermal conductivity is:
Which of the following correctly represents the SI unit of thermal conductivity?
Which of the following substances has the minimum value of thermal conductivity ?
- The rate of flow of heat through a simple homogeneous solid is directly proportional to the area of the section at right angles to the direction of heat flow, and _______.
Where K and σ are thermal and electrical conductivities in a solid, according to Wiedemann-Franz law
