Thermal Ohm’s law analogy in power electronics In thermal analysis of electronic devices, the so-called ‘‘thermal Ohm’s law’’ is written as ΔT = P * R_th, where ΔT is the temperature rise, P is the power loss, and R_th is thermal resistance. In this analogy, temperature and power loss correspond to which electrical quantities in Ohm’s law?

Introduction / Context:
Thermal modeling of electronics often borrows the language of electrical circuits. The relationship ΔT = P * R_th mirrors the familiar V = I * R, letting engineers use intuitive circuit methods to estimate heat flow and temperature rise in heat sinks, packages, and PCBs.

Given Data / Assumptions:

• Thermal Ohm’s law: ΔT = P * R_th.
• Electrical Ohm’s law: V = I * R.
• R_th represents thermal resistance between two nodes (e.g., junction to ambient).

Concept / Approach:
Map each thermal quantity to an electrical counterpart so the forms of both laws coincide. The temperature difference plays the role of potential difference, power dissipation plays the role of current, and thermal resistance parallels electrical resistance.

Step-by-Step Solution:
Start from ΔT = P * R_th.Compare with V = I * R.Therefore, ΔT ↔ V, P ↔ I, and R_th ↔ R.So, temperature corresponds to voltage, and power loss corresponds to current.

Verification / Alternative check:
Heat flow rate Q_dot (watts) is analogous to electric current I (amperes). A larger power dissipation drives a larger ‘‘flow’’ of heat through a fixed thermal resistance, creating a larger temperature drop, just as higher current through a resistor creates a larger voltage drop.

Why Other Options Are Wrong:
Option B: Swaps the mapping and breaks the form of the law.
Option C/D: Misassigns thermal resistance or mixes quantities inconsistently with ΔT = P * R_th.

Common Pitfalls:
Confusing absolute temperature with temperature rise; the analogy applies to differences (ΔT vs V), not absolute values. Also, thermal capacitance analogies are separate (for transients) and do not change the basic static mapping.

Final Answer:
V and I respectively of ohm's law