72 + Interview Questions in Bioelectric Signal And Electrodes in Biomedical Instrumentation Page 2 InterviewSolution

51.	Electrodes to measure EEG are placed on ________(a) forehead(b) scalp(c) cheek(d) earsI have been asked this question in quiz.This intriguing question comes from Electrodes for EEG in division Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct OPTION is (b) SCALP The explanation is: Electrode to measure EEG are PLACED on the scalp. The position of each electrode is specified USING the INTERNATIONAL 10/20 system. Each electrode site is labeled with a letter and a number.

Discussion

52.	In voluntary contraction of the skeletal muscles, the muscle potential ranges from ________(a) 50 uV – 5 mV(b) 50 mV – 5 V(c) 0.05 uV – 2 mV(d) 50 mV – 500 mVThe question was asked during an interview.This intriguing question originated from Electrodes for EMG topic in chapter Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct answer is (a) 50 uV – 5 mV To EXPLAIN I would say: In voluntary CONTRACTION of the skeletal MUSCLES, the muscle potential ranges from 50 uV – 5 mV and duration from 2 to 15 MS. The values vary with the anatomic position of the muscle and the SIZE and location of the electrode. In a relaxed muscle there are no action potentials.

Discussion

53.	On increasing the chloride deposit the Ag-AgCl electrode ______________(a) increases the impedance(b) reduces impedance(c) has no effect on impedance(d) cannot be determinedI got this question by my college director while I was bunking the class.The doubt is from Silver-Silver Chloride Electrodes in chapter Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» CORRECT answer is (a) INCREASES the impedance Easiest explanation: Studies have shown that the impedance of the electrode was different LAYERS of chloride. There is an optimum chloriding, which gives the LOWEST impedance.Above and below that value the impedance is high.

Discussion

54.	What is the frequency range of ECG?(a) 70-120 Hz(b) 0.05-120 Hz(c) 5-120 Hz(d) 12-120 HzI have been asked this question during a job interview.Question is from Recording Electrodes topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct OPTION is (b) 0.05-120 Hz Easiest explanation: PRIMARY signal CHARACTERISTICS of ECG are: Frequency RANGE: 0.05-120 Hz. Signal AMPLITUDE: 0.1-5 mV. Typical signal: 1mV.

Discussion

55.	Buffer amplifier converts ____________(a) low impedance signals to high impedance signals(b) high impedance signals to low impedance signals(c) ac impedance signals to dc impedance signals(d) dc impedance signals to ac impedance signalsThe question was posed to me during an interview.I need to ask this question from Electrodes for ECG in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» RIGHT option is (b) high IMPEDANCE signals to low impedance signals The best I can explain: Noise is typically generated from MOTION artefacts and power LINE interference. A common solution used to suppress noise in dry electrode signals is a buffer amplifier. Abuffer amplifies is essentially an impedance CONVERTER, that converts high impedance signals to low impedance signals.

Discussion

56.	Atrio ventricular node is located at __________(a) upper part of the heart wall between the two atrial(b) lower part of the heart wall above the two atrial(c) lower part of the heart wall between the two atrial(d) upper part of the heart wall above the two atrialI had been asked this question in an internship interview.I'm obligated to ask this question of Electrodes for ECG topic in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» RIGHT choice is (c) lower part of the heart wall between the TWO atrial To explain I would say: The AV node is located in the lower part of the wall between the two atria. The AV node DELAYS the spread of excitation for about 0.12s, due to the presence of a fibrous barrier of non-excitable cells that effectively prevent its propagation from continuing BEYOND the limits of stria.

Discussion

57.	Electrode paste ____________(a) increases contact impedance(b) equates contact impedance(c) reduces contact impedance(d) absorbs contact impedanceThe question was posed to me in examination.Query is from Recording Electrodes in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct option is (c) reduces contact impedance Easy explanation: In order to obtain a clearly established contact (low contact impedance) an electrolyte or electrode paste is usually employed as an interface between the electrode and the surface of the SOURCE of the event. It is placed between the skin and the electrode. It HELPS to get BETTER signal ACQUISITION.

Discussion

58.	Deep-seated electrodes indicates the electric potential difference arising ________ the living tissues or cells.(a) inside(b) outside(c) around(d) adjacentI got this question in unit test.This question is from Recording Electrodes in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Right option is (a) inside The EXPLANATION is: Deep-seated ELECTRODES indicate the electric potential difference arising inside the living tissues or CELLS. SURFACE electrodes indicates the electric potentials arising outside the living tissues that is on the surface of the SKIN. Needle electrodes are example of deep seated electrodes.

Discussion

59.	The letter T in the EEG electrode placement system denotes?(a) temporal lope(b) temper lobe(c) trace(d) timpanicI got this question by my college director while I was bunking the class.The origin of the question is Electrodes for EEG in division Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct answer is (a) TEMPORAL lope The best I can explain: T denotes temporal lobe of the head. The POSITION of each electrode is specified using the International 10/20 system. Each electrode SITE is labeled with a LETTER and a number.

Discussion

60.	Recording electrical activities associated with heart is known as ____________(a) EEG(b) EOG(c) EMG(d) ECGI got this question during a job interview.This key question is from Electrodes for ECG in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» RIGHT choice is (d) ECG To EXPLAIN I would say: The recording of the electrical ACTIVITIES associated with the FUNCTIONING of the heart is known as electrocardiogram. ECG is a quasi-periodical, rhythmically repeating signals synchronized by the function of the heart, which acts as a generator of bioelectric EVENTS. This generated signals can be described by the means of a simple electric dipole.

Discussion

61.	Normal EEG frequency range is _______(a) 50-500Hz(b) 0.5-50HZ(c) 0.05-5Hz(d) 1-200HzThis question was posed to me in an online interview.This intriguing question comes from Electrodes for EEG topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Right option is (b) 0.5-50HZ To explain I would SAY: The FREQUENCY varies greatly with different BEHAVIORAL STATES. The normal EEG frequency content RANGES from 0.5 to 50Hz. The nature of the wave varies over the different parts of the scalp.

Discussion

62.	Ag-AgClelectrodes are ___________(a) polarized(b) non-polarized(c) partially polarized(d) cannot be saidThe question was posed to me in an online quiz.Question is from Silver-Silver Chloride Electrodes topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct OPTION is (b) non-polarized Easy explanation: The most important and desirable property of the ELECTRODES designed to pick up signals from biological objects is that they should not polarize. This means that the electrodes POTENTIAL must not vary CONSIDERABLY even when current passes through it. Electrodes made of Ag-AgCl YIELD acceptable standards of performance.

Discussion

63.	The peak to peak amplitude of the waves that can be picked from the scalp is ______________(a) 100mV(b) 100V(c) 100uV(d) 10mVI have been asked this question in a job interview.This intriguing question comes from Electrodes for EEG in division Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct option is (c) 100uV Best explanation: The EEG signal can be PICKED up with ELECTRODES either from the scalp or directly from the cerebral CORTEX. The peak to peak amplitude of the waves that can be picked up from the scalp is normally 100uV. The frequency varies greatly with DIFFERENT behavioral states.

Discussion

64.	The delta wave in EEG ranges from ___________(a) 0.5-4Hz(b) 4-8Hz(c) 8-13Hz(d) 13-22HzThis question was addressed to me in an internship interview.My enquiry is from Electrodes for EEG topic in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct ANSWER is (a) 0.5-4Hz The best EXPLANATION: The DELTA wave in EEG ranges from 0.5-4Hz. The theta wave in EEG ranges from 4-8Hz. The alpha wave in EEG ranges from 8-13Hz and BETA from 13-22Hz.

Discussion

65.	The ground electrode is usually positioned over which body structures?(a) bony(b) hairy(c) fleshy(d) sweatyThe question was posed to me by my school teacher while I was bunking the class.This key question is from Electrodes for EMG in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct CHOICE is (a) bony The best EXPLANATION: The ground electrode is usually positioned over bony structures rather than over large muscle masses, in the vicinity of the recording and stimulating electrodes, and where possible, EQUIDISTANT from them. Hairy areas don’t transmit PROPER SIGNALS. It increases impedance of the skin.

Discussion

66.	Which of the following is a preferred electrode for measuring EMG?(a) surface electrodes(b) needle electrodes(c) pregelled electrodes(d) scalp electrodesThe question was asked in final exam.The above asked question is from Electrodes for EMG in chapter Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The CORRECT answer is (b) needle electrodes The best explanation: Electrodes for EMG WORK are usually of the needle type. Needle electrodes are used in clinical EMG, neurography and other electrophysiological measurements of the muscle tissues underneath the skin. Surface electrodes are PREFERRED to measure ECG. SCALP electrodes for EEG.

Discussion

67.	Which rhythm is the principal component of the EEG that indicates the alertness of the brain?(a) theta rhythm(b) gamma rhythm(c) beta rhythm(d) alpha rhythmI have been asked this question in my homework.Asked question is from Electrodes for EEG in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct OPTION is (d) alpha rhythm Explanation: The alpha rhythm is the PRINCIPAL component of the EEG and is an indicator of the STATE of alertness of the brain. It serves as an indicator of the depth of anesthesia in the operating room. The frequency of the EEG seems to be AFFECTED by the mental activity of a person.

Discussion

68.	Which of the following is a wireless ECG acquiring system?(a) pregelled disposable electrodes(b) limb electrodes(c) pasteless electrodes(d) smart padThe question was posed to me in an online quiz.My question is based upon Electrodes for ECG topic in division Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The CORRECT option is (d) smart pad The explanation: Smart pad is a system that DISPLAYS patients electrocardiogram signals without adhesive pads, WIRES or active intervention from a clinician. The system automatically selects three electrodes from an array of Cu/Ni fabric BASED electrodes patterned on a thin pad on which the patient lies. The selected electrodes are USED to provide a differential 3 lead measurement of the patient’s ECG, which is then transmitted wirelessly and displayed on a laptop computer.

Discussion

69.	Impedance pneumography is a commonly-used technique to monitor a person’s _______(a) respiration rate(b) heart rate(c) pulse rate(d) skin impedanceI have been asked this question by my school principal while I was bunking the class.I need to ask this question from Recording Electrodes in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct option is (a) respiration rate To explain I would SAY: Impedance pneumography is a commonly-used technique to monitor a person’s respiration rate, or breathing rate. It is implemented by using two electrodes or FOUR electrodes. Skin impedance is the resistance between the skin and the ELECTRODE. Heart rate measurement is called ECG.

Discussion

70.	MRI stands for ____________(a) Mechanical Resonance Imaging(b) Magnetic Resonance Imaging(c) Mutually Related Imaging(d) Magnetic Resultant ImagingThe question was posed to me in an interview.Origin of the question is Silver-Silver Chloride Electrodes topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» Correct CHOICE is (b) Magnetic Resonance Imaging Easiest explanation: MRI stands for Magnetic Resonance Imaging. The MRI is a diagnostic TECHNIQUE that uses magnetic fields and radio waves to produce a detailed picture of soft tissues and body bones. An MR mirrors the SPINE using a magnet crossing the body to EXCITE hydrogen ATOMS.

Discussion

71.	EKG stands for _________________(a) Electrocardiography(b) Electroencephalography(c) Electromyography(d) ElectrtokinetcographyThe question was asked by my college director while I was bunking the class.The origin of the question is Origin of Bioelectric Signals in chapter Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct answer is (a) Electrocardiography For explanation: Electrocardiography (ECG or EKG) is the way toward recording the electrical action of the HEART over some STRETCH of time utilizing anodes put on the skin. It could simply be understood as the electrical REPRESENTATION of heart beat. ELECTROENCEPHALOGRAPHY is the electrical recording of brain.

Discussion

72.	What is the relatively static membrane potential of quiescent cells called?(a) half-cell potential(b) action potential(c) resting membrane potential(d) cell potentialThe question was posed to me in an interview for internship.The question is from Origin of Bioelectric Signals topic in division Bioelectric Signal and Electrodes of Biomedical Instrumentation
Answer» The correct option is (c) resting membrane potential The best I can EXPLAIN: Resting membrane potential or the resting potential is the RELATIVE STATIC membrane potential of quiescent cell. That is if the resting membrane potential of a neuron is about -70 mV (mV=millivolt) it MEANS that the INSIDE of the neuron is 70 mV less than the outside of the neuron. An action potential occurs when the potential of the membrane of a given axonal position increases and decreases rapidly. This depolarization causes depolarization of adjacent positions in a similar way.

Discussion

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Electrodes to measure EEG are placed on ________(a) forehead(b) scalp(c) cheek(d) earsI have been asked this question in quiz.This intriguing question comes from Electrodes for EEG in division Bioelectric Signal and Electrodes of Biomedical Instrumentation

What is the frequency range of ECG?(a) 70-120 Hz(b) 0.05-120 Hz(c) 5-120 Hz(d) 12-120 HzI have been asked this question during a job interview.Question is from Recording Electrodes topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation

Electrode paste ____________(a) increases contact impedance(b) equates contact impedance(c) reduces contact impedance(d) absorbs contact impedanceThe question was posed to me in examination.Query is from Recording Electrodes in section Bioelectric Signal and Electrodes of Biomedical Instrumentation

Recording electrical activities associated with heart is known as ____________(a) EEG(b) EOG(c) EMG(d) ECGI got this question during a job interview.This key question is from Electrodes for ECG in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation

Normal EEG frequency range is _______(a) 50-500Hz(b) 0.5-50HZ(c) 0.05-5Hz(d) 1-200HzThis question was posed to me in an online interview.This intriguing question comes from Electrodes for EEG topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation

Ag-AgClelectrodes are ___________(a) polarized(b) non-polarized(c) partially polarized(d) cannot be saidThe question was posed to me in an online quiz.Question is from Silver-Silver Chloride Electrodes topic in section Bioelectric Signal and Electrodes of Biomedical Instrumentation

The delta wave in EEG ranges from ___________(a) 0.5-4Hz(b) 4-8Hz(c) 8-13Hz(d) 13-22HzThis question was addressed to me in an internship interview.My enquiry is from Electrodes for EEG topic in portion Bioelectric Signal and Electrodes of Biomedical Instrumentation