CABT Fundamentals of Electronics 2

Question 1

A capacitor is connected in series with a resistor to an AC source. As frequency increases, what happens to the capacitive reactance (Xc)?

Accepted Answer

Xc decreases

Answer

Capacitive reactance Xc = 1/(2πfC), so as frequency increases, Xc decreases.

Question 2

In a biomedical device, a zener diode is used primarily to:

Accepted Answer

Regulate voltage

Answer

Zener diodes operate in reverse breakdown to maintain a stable reference voltage, making them ideal for voltage regulation.

Question 3

What is the time constant (τ) of an RC circuit with R = 10 kΩ and C = 100 µF?

Accepted Answer

1 second

Answer

τ = RC = 10,000 Ω × 0.0001 F = 1 second.

Question 4

Which type of amplifier configuration provides both voltage gain and current gain but with a 180° phase shift?

Accepted Answer

Common emitter

Answer

The common emitter configuration inverts the output signal (180° phase shift) and provides both voltage and current gain.

Question 5

In an ECG machine, the CMRR (Common Mode Rejection Ratio) specification is important because it:

Accepted Answer

Rejects 60 Hz power line interference

Answer

High CMRR allows the differential amplifier to reject common-mode noise such as 60 Hz interference from power lines while amplifying the ECG signal.

(CABT) Certified Associate in Biomedical Technology Practice Test