Impedance is:

Impedance is:

• A. Used in analytic instruments to stop a test
• B. Blockage of light or electric current in analytic instruments
• C. Lack of synchronicity between the jugular pulse and the heartbeat
• D. Inability to feel pedal pulses

Answer: (B)

Impedance is about opposition to the flow of electric current. In analytic instruments that use electrical impedance, particles or cells passing through a sensing region momentarily obstruct the current, causing a measurable change that the instrument converts into a pulse or count. This is the principle behind devices like cell counters, where each obstruction corresponds to a particle and the size can alter the pulse magnitude. The idea of blocking light describes optical sensors, not impedance, so that part doesn’t fit with how impedance works. The other options describe physiological signs or rhythms, which aren’t related to how impedance is used in laboratory instrumentation.

Impedance is about opposition to the flow of electric current. In analytic instruments that use electrical impedance, particles or cells passing through a sensing region momentarily obstruct the current, causing a measurable change that the instrument converts into a pulse or count. This is the principle behind devices like cell counters, where each obstruction corresponds to a particle and the size can alter the pulse magnitude.

The idea of blocking light describes optical sensors, not impedance, so that part doesn’t fit with how impedance works. The other options describe physiological signs or rhythms, which aren’t related to how impedance is used in laboratory instrumentation.