What should be checked about electrode condition before use?

• A. They are placed behind the ear
• B. They are not expired or dried out
• C. They match in color
• D. They have a built-in battery

Answer: (B)

The essential idea is that electrodes must be ready to conduct signals reliably. If they’re expired or dried out, their conductive gel or electrolyte can degrade, raising impedance at the skin contact. That makes signal transmission noisy or weak and can lead to inaccurate readings or poor adhesion. Checking that the electrodes are within their expiration date and still moist enough (not dried out) ensures good skin contact, low impedance, and safe, effective monitoring.

Other details like where they’re placed, color, or whether they have a battery don’t speak to their current conductive condition. Placement is about application, color is cosmetic, and a built-in battery only matters for specific wireless designs, not the electrode’s general readiness.