Short Answer
Equilibrium voltage across a membrane for a given ion at specified concentration gradient is the best answer.
Biophysics questions work best when you translate anatomy or instrumentation back into plain physics: pressure gradients, flow, diffusion, energy deposition, imaging contrast, and signal-to-noise.
Nernst equation: E = (RT/zF) ln([ion]_out/[ion]_in) gives the equilibrium potential at which electrochemical forces balance for a single ion species.
Why This Answer Is Correct
This is a Medium-level question in Biophysics & Medical Physics. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Clinical wording can hide a simple physics core. Strip the scenario down to transport, force, energy, or measurement first.
Choices At A Glance
- A. Membrane capacitance
- B. Equilibrium voltage across a membrane for a given ion at specified concentration gradient
- C. Action potential speed
- D. Diffusion constant of water
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Study Next
Review the related formula library
study the medical physics track
Topic Snapshot
Topic: Biophysics & Medical Physics
Difficulty: Medium
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.