CABT Fundamentals of Electronics 5

Question 1

What type of feedback is used in most biomedical amplifier designs to stabilize gain and improve linearity?

Accepted Answer

Negative feedback

Answer

Negative feedback reduces gain but improves stability, linearity, bandwidth, and reduces distortion — essential characteristics for accurate biomedical signal amplification.

Question 2

A defibrillator capacitor stores 360 joules at 5000 V. What is the capacitance value?

Accepted Answer

28.8 µF

Answer

Energy E = ½CV², so C = 2E/V² = 2×360/(5000²) = 28.8 µF.

Question 3

In a pulse oximeter, photodetectors measure light absorption at two wavelengths. Which wavelengths are typically used?

Accepted Answer

660 nm and 940 nm

Answer

Pulse oximeters use red light (~660 nm) and infrared light (~940 nm) because oxyhemoglobin and deoxyhemoglobin have distinct absorption differences at these wavelengths.

Question 4

What is the Nyquist theorem's requirement for sampling an analog signal to avoid aliasing?

Accepted Answer

Sample at least twice the highest frequency in the signal

Answer

The Nyquist theorem states that the sampling rate must be at least twice the highest frequency component of the signal to accurately reconstruct it without aliasing.

Question 5

In a biomedical pressure transducer using a strain gauge, what electrical parameter changes in response to physical deformation?

Accepted Answer

Resistance

Answer

Strain gauges work on the piezoresistive principle — mechanical deformation changes the geometry of the conductor, altering its electrical resistance.

(CABT) Certified Associate in Biomedical Technology Practice Test

(CABT) Certified Associate in Biomedical Technology Practice Test

CABT Fundamentals of Electronics 5