COMPLETE REAL EXAM QUESTIONS AND CORRECT VERIFIED
ANSWERS/ ALREADY GRADED A+
(MOST RECENT!!)
SECTION 1: EEG INSTRUMENTATION & ELECTRONICS (Questions 1–36)
1. The basic unit for measuring current flow is the:
A) Ohm
B) Volt
C) Ampere
D) Coulomb
Answer: C) Ampere
Rationale: The ampere (A) is the SI base unit for electric current, measuring the
rate of electron flow in a circuit. Ohm measures resistance, Volt measures
potential, Coulomb measures charge.
2. Which component of an EEG machine stores electrical energy?
A) Resistor
B) Inductor
C) Capacitor
D) Transformer
Answer: C) Capacitor
Rationale: A capacitor stores energy in an electric field between two conductive
plates separated by a dielectric. It is used in filters and power supplies.
3. The standard paper speed for a routine EEG is:
A) 15 mm/second
B) 30 mm/second
C) 60 mm/second
D) 10 mm/second
Answer: B) 30 mm/second
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,Rationale: ACNS guidelines specify 30 mm/sec. This allows a standard 10-second
epoch per page, balancing temporal resolution and waveform readability.
4. What is the recommended maximum electrode impedance for routine EEG?
A) 1,000 ohms
B) 5,000 ohms
C) 10,000 ohms
D) 20,000 ohms
Answer: B) 5,000 ohms (5 kΩ)
Rationale: Impedance should be below 5 kΩ and balanced (within 500 Ω) across
electrodes. Higher impedances reduce common-mode rejection and introduce
noise.
5. A differential amplifier:
A) Amplifies only the difference between two inputs
B) Amplifies only the common signal between two inputs
C) Amplifies both equally
D) Converts AC to DC
Answer: A) Amplifies only the difference between two inputs
Rationale: The differential amplifier amplifies the voltage difference (V1 - V2)
while rejecting identical signals common to both inputs via Common-Mode
Rejection Ratio (CMRR).
6. The filter settings that create a very narrow band pass (rarely used clinically)
are:
A) LF 1.0 Hz and HF 70 Hz
B) LF 5.0 Hz and HF 15 Hz
C) LF 0.5 Hz and HF 35 Hz
D) LF 10 Hz and HF 100 Hz
Answer: B) LF 5.0 Hz and HF 15 Hz
Rationale: A 5–15 Hz bandpass filters out clinically critical delta, theta, and beta
activity. Such narrow filters distort waveforms and should only be used for
specific artifact troubleshooting, never for routine interpretation.
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,7. If the calibration input voltage is changed from 50 µV to 100 µV, the amplitude
of the recorded cerebral activity will:
A) Double
B) Halve
C) Remain unchanged
D) Appear inverted
Answer: C) Remain unchanged
Rationale: The calibration signal is separate from the patient's biological signal.
Changing calibration voltage affects only the calibration square wave, not the
EEG.
8. A spike measures 16 mm peak-to-peak at 7 µV/mm sensitivity. Its amplitude is:
A) 112 µV
B) 56 µV
C) 224 µV
D) 16 µV
Answer: A) 112 µV
Rationale: Amplitude = measured deflection (mm) × sensitivity (µV/mm) = 16 × 7
= 112 µV.
9. The time constant (TC) of an EEG amplifier is directly related to which filter?
A) High-frequency filter
B) Low-frequency filter
C) Notch filter
D) 60 Hz filter
Answer: B) Low-frequency filter
Rationale: The time constant (in seconds) is determined by the low-frequency (LF)
filter. TC = 1 / (2π × LF cutoff). A longer TC allows slower frequencies to pass.
10. The standard high-frequency (HF) filter setting for adult routine EEG is:
A) 15 Hz
B) 35 Hz
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, C) 70 Hz
D) 100 Hz
Answer: C) 70 Hz
Rationale: 70 Hz is standard to attenuate high-frequency noise (e.g., EMG) while
preserving EEG frequencies up to the beta range (13–30+ Hz).
11. A notch filter is designed to eliminate:
A) Muscle artifact
B) Eye blink artifact
C) 60 Hz AC interference
D) Sweat artifact
Answer: C) 60 Hz AC interference
Rationale: A notch filter (typically 60 Hz in the US, 50 Hz in Europe) specifically
attenuates a very narrow band around mains frequency without affecting
adjacent EEG frequencies.
12. The sensitivity setting of 10 µV/mm means:
A) 10 µV of input produces 1 mm of pen deflection
B) 1 µV of input produces 10 mm of pen deflection
C) 10 µV of input produces 10 mm of pen deflection
D) 100 µV produces 1 mm
Answer: C) 10 µV of input produces 10 mm of pen deflection
Rationale: Sensitivity is the ratio of input voltage to pen deflection. At 10 µV/mm,
a 10 µV signal moves the pen 1 mm. Higher sensitivity (lower number) amplifies
small signals more.
13. Which of the following is a referential montage?
A) Fp1-F7, F7-T3, T3-T5, T5-O1
B) Fp1-A1, F7-A1, T3-A1, T5-A1
C) Fp1-F3, F3-C3, C3-P3, P3-O1
D) Fp1-Fp2, F3-F4, C3-C4
Answer: B) Fp1-A1, F7-A1, T3-A1, T5-A1
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