Which of the following impedance values would NOT be acceptable for EEG electrode contact quality?

Which of the following impedance values would NOT be acceptable for EEG electrode contact quality?

• A. Less than 5kΩ
• B. Less than 5Ω
• C. Less than 10kΩ
• D. At least 10Ω

Answer: (B)

Understanding EEG electrode contact quality hinges on impedance being low enough to minimize noise while staying in a physiologically plausible range. In EEG setup, impedances are typically reported in kilo-ohms and kept under about 5 kΩ (often aiming for 2–5 kΩ) to reflect a good skin–electrode connection. Values expressed in ohms—such as less than 5 ohms—are not realistic for properly placed scalp electrodes and would indicate a measurement artifact or a short circuit, which would degrade data quality. Hence, something that reads below a few ohms would not be acceptable. The other ranges fall within or are plausible given standard guidelines for electrode impedance.

Understanding EEG electrode contact quality hinges on impedance being low enough to minimize noise while staying in a physiologically plausible range. In EEG setup, impedances are typically reported in kilo-ohms and kept under about 5 kΩ (often aiming for 2–5 kΩ) to reflect a good skin–electrode connection. Values expressed in ohms—such as less than 5 ohms—are not realistic for properly placed scalp electrodes and would indicate a measurement artifact or a short circuit, which would degrade data quality. Hence, something that reads below a few ohms would not be acceptable. The other ranges fall within or are plausible given standard guidelines for electrode impedance.