Test your knowledge of biomedical signals with this 10-question quiz. Select the best answer for each question, then check your score and review the explanations.
Answers and Explanations
1. Which of the following biomedical signals measures the electrical activity of the heart?
Correct Answer: B. Electrocardiogram (ECG)
The electrocardiogram (ECG or EKG) records the electrical activity of the heart. It's used to diagnose various cardiac conditions by measuring the depolarization and repolarization of heart muscle cells.
2. What is the typical frequency range of an ECG signal?
Correct Answer: B. 0.05 Hz to 100 Hz
ECG signals typically have frequency components between 0.05 Hz and 100 Hz. The lower frequency components (below 0.5 Hz) can be affected by baseline wander, while higher frequencies (above 100 Hz) contain minimal diagnostic information.
3. Which electrode configuration is commonly used in ECG recordings to measure the electrical potential between the right arm, left arm, and left leg?
Correct Answer: C. Einthoven's triangle
Einthoven's triangle refers to the configuration of three limb electrodes (right arm, left arm, and left leg) that form an equilateral triangle with the heart at the center. This configuration allows measurement of three standard ECG leads (I, II, and III).
4. The electromyogram (EMG) signal measures:
Correct Answer: C. Electrical activity of muscles
Electromyography (EMG) records the electrical activity produced by skeletal muscles. It's used to assess muscle function and diagnose neuromuscular disorders by detecting the electrical potentials generated during muscle contraction.
5. What is the main challenge in recording biomedical signals?
Correct Answer: B. Low amplitude of signals and high levels of noise
Biomedical signals are typically very weak (microvolts to millivolts) and are often contaminated by various noise sources including power line interference, motion artifacts, and physiological noise from other body systems.
6. Which frequency band in EEG signals is associated with relaxed, awake states with eyes closed?
Correct Answer: C. Alpha (8-13 Hz)
Alpha waves (8-13 Hz) are most prominent when a person is awake but relaxed with eyes closed. They are strongest in the occipital region and diminish with eye opening or mental effort.
7. The P wave in an ECG represents:
Correct Answer: B. Atrial depolarization
The P wave corresponds to atrial depolarization, which initiates atrial contraction. This is followed by the QRS complex (ventricular depolarization) and T wave (ventricular repolarization).
8. What is the typical amplitude range of surface EMG signals?
Correct Answer: B. 0.5-5 mV
Surface EMG signals typically range from 0.5 to 5 mV peak-to-peak, though this can vary based on factors like muscle type, electrode placement, and contraction level. Needle EMG signals can be much smaller.
9. Which of the following is NOT a common noise source in biomedical signal acquisition?
Correct Answer: D. Quantum fluctuations
While quantum fluctuations exist at a fundamental level, they are not a significant practical concern in typical biomedical signal acquisition. Common noise sources include power line interference (50/60 Hz), baseline wander (low frequency), motion artifacts, and physiological interference from other body systems.
10. What is the primary purpose of an instrumentation amplifier in biomedical signal acquisition?
Correct Answer: B. To amplify weak differential signals while rejecting common-mode noise
Instrumentation amplifiers are specifically designed to amplify the small differential voltage between two input terminals (the biomedical signal) while rejecting any common-mode voltage (noise that appears equally on both inputs, like power line interference).