When electrical signals from external sources interfere with signals derived from the patient, this is referred to as:

When electrical signals from external sources interfere with signals derived from the patient, this is referred to as:

• A. Resistance
• B. Stray capacitance
• C. Cell potential
• D. Biopotentiallity

Answer: (B)

External interference on biopotential recordings happens when signals from outside couple into the patient lead system. This is explained by stray capacitance: parasitic capacitance between the leads, the patient, and the surrounding environment allows alternating current from outside sources (like power lines or electronic devices) to pass into the recording and show up as noise. Proper shielding, grounding, and differential amplification reduce this coupling and keep the true biopotential signal clearer. The other terms don’t describe how external signals enter the measurement—resistance affects current magnitude but isn’t the coupling mechanism, cell potential is about the voltage across a cell membrane, and the term biopotentiallity isn’t a standard descriptor for this phenomenon.

External interference on biopotential recordings happens when signals from outside couple into the patient lead system. This is explained by stray capacitance: parasitic capacitance between the leads, the patient, and the surrounding environment allows alternating current from outside sources (like power lines or electronic devices) to pass into the recording and show up as noise. Proper shielding, grounding, and differential amplification reduce this coupling and keep the true biopotential signal clearer. The other terms don’t describe how external signals enter the measurement—resistance affects current magnitude but isn’t the coupling mechanism, cell potential is about the voltage across a cell membrane, and the term biopotentiallity isn’t a standard descriptor for this phenomenon.