Transistor operated as a variable resistor: Does this operating mode imply a device property called “transistance,” or is that terminology incorrect in modern electronics?

Introduction / Context:Transistors can be biased so the device behaves like a controllable resistor over a limited range (for BJTs via small-signal r_e around a bias point; for MOSFETs in the ohmic/triode region). This question probes terminology: is there a recognized property called “transistance,” or is the correct language something else such as transconductance (g_m) or small-signal resistance?

Given Data / Assumptions:

• Small-signal linearization around a fixed quiescent point.
• BJT or FET used as a variable resistor in an analog control context.
• Standard modern electronics terminology.

Concept / Approach:In small-signal models, a BJT exhibits transconductance g_m = ΔI_C / ΔV_BE and a dynamic emitter resistance r_e ≈ 25 mV / I_E (at room temperature). A MOSFET in triode region has a channel resistance that varies with gate and drain-source biases. Neither case uses the term “transistance” in contemporary practice. Another concept, “transresistance,” refers to an amplifier whose output is a voltage proportional to input current (units of ohms), but that is not the same as a device property named “transistance.” Thus, claiming a transistor “has transistance” when used as a variable resistor is incorrect terminology.

Step-by-Step Solution:

Verification / Alternative check:Review of device models (Ebers–Moll, hybrid-π, MOS Level models) shows g_m, r_π, r_o for BJTs and g_m, r_ds for MOSFETs; “transistance” does not appear as a canonical parameter.

Why Other Options Are Wrong:Conditioning on device type, temperature, or beta does not legitimize nonstandard terminology.

Common Pitfalls:Confusing “transresistance amplifier” (a circuit type) with an intrinsic device property; mixing up g_m with resistance concepts.

Final Answer:Incorrect