R.EEG.T part 3
A 60uV wave at a sensitivity of 6uV/mm will produce a deflection of(have an amplitude
of) - answer A=10mm (deflection or amplitude)
A 10mm deflection at a sensitivity setting of 20uV/mm will have a voltage of? -
answer200uV
15mm 10uV/mm-what’s the voltage? - answer150uV
100uV 10uv/mm-what’s the deflection? - answer10mm
State the equation to solve for frequency using duration? - answer
Frequency=1/duration
State the equation to determine the duration of a wave - answer Duration=distance/time
base
What is the duration of a wave with a distance of 10 mm and a known time base of 30
mm/sec - answer.33second- 10mm/30mm/sec
What is the duration of a wave with a distance of 5mm and a known timebase of
24mm/sec - answer.21sec- 5mm/24mm/sec
What is the frequency of a wave with a duration of .40second? - answer2.5hz-1/.40
Describe an A/D converter - answera device that converts the continuous analog EEG
signal to numbers or digits; this conversion is done by sampling the epoch of EEG at
pre-selected intervals and recording the polarity and amplitude of the wave at each of
those points
What should the analog to digital conversion specifications be for a digital EEG
instrument? - answerGreater than or equal to 12 bit ADC.
What should the input impedance be for a digital EEG instrument? - answerGreater
than 10megaohms
What should the common mode rejection ratio be for a digital EEG instrument? -
answerShould be at least 90 dB
Define sampling rate - answerthe number of digital points per second used to represent
the analog signal; sampling rate=number of points/analysis time
, What should the sampling rate be for a digital EEG instrument? - answerA minimum of
200Hz, preferably 250 to 400 Hz
Describe the effects of digital filtering on a waveform - answerDigital filtering causes a
phase shift where the waveform appears to be advanced or delayed in time. Excessive
LFF causes a shift to the left. Excessive HFF causes a shift to the right.
Define the Nyquist frequency - answerit is also known as the critical sampling rate; it
must be at least twice the fastest frequency; if the sample is slower, then aliasing may
occur
Define aliasing - answerwhen the ADC aka analog digital converter samples the analog
signal at a rate LESS than two times its fastest frequency and the analog signal is then
misinterpreted as a slower frequency waveform
What are the Ohm's Law equations? - answerE = I x R. E = voltage
I = E / R. I = current
R = E / I. R = resistance
How many amperes of current will flow in a circuit containg a 2 V battery and 10 ohms
of resistance? - answer0.2 amperes (I)
How many Volts are needed to produce a 20 amp current with a 2 ohm resistance? -
answer40V
Define resistance - answerThe inability of a part of a circuit to allow the passage of
direct (constant voltage) current
Define impedance - answerImpedance is the resistance of a part of a circuit to the
passage of alternating current
Where is the nasion - answera. the indentation between the forehead and the nose
Where is the Inion? - answerthe bony protuberance in the middle of the back of the
head; a ridge or knob that can be felt when you run your finger up the back of the neck
to the skull.
List the standard skull landmarks used in the International 10-20 System. - answerInion,
nasion, L/R preauricular
If the measurement from F8 through Fz to F7 measures 24cm, what are the
measurements to mark F4 and F3 If the zero remains at F8? - answerF8-F4=6cm F8-
F3=18cm
A 60uV wave at a sensitivity of 6uV/mm will produce a deflection of(have an amplitude
of) - answer A=10mm (deflection or amplitude)
A 10mm deflection at a sensitivity setting of 20uV/mm will have a voltage of? -
answer200uV
15mm 10uV/mm-what’s the voltage? - answer150uV
100uV 10uv/mm-what’s the deflection? - answer10mm
State the equation to solve for frequency using duration? - answer
Frequency=1/duration
State the equation to determine the duration of a wave - answer Duration=distance/time
base
What is the duration of a wave with a distance of 10 mm and a known time base of 30
mm/sec - answer.33second- 10mm/30mm/sec
What is the duration of a wave with a distance of 5mm and a known timebase of
24mm/sec - answer.21sec- 5mm/24mm/sec
What is the frequency of a wave with a duration of .40second? - answer2.5hz-1/.40
Describe an A/D converter - answera device that converts the continuous analog EEG
signal to numbers or digits; this conversion is done by sampling the epoch of EEG at
pre-selected intervals and recording the polarity and amplitude of the wave at each of
those points
What should the analog to digital conversion specifications be for a digital EEG
instrument? - answerGreater than or equal to 12 bit ADC.
What should the input impedance be for a digital EEG instrument? - answerGreater
than 10megaohms
What should the common mode rejection ratio be for a digital EEG instrument? -
answerShould be at least 90 dB
Define sampling rate - answerthe number of digital points per second used to represent
the analog signal; sampling rate=number of points/analysis time
, What should the sampling rate be for a digital EEG instrument? - answerA minimum of
200Hz, preferably 250 to 400 Hz
Describe the effects of digital filtering on a waveform - answerDigital filtering causes a
phase shift where the waveform appears to be advanced or delayed in time. Excessive
LFF causes a shift to the left. Excessive HFF causes a shift to the right.
Define the Nyquist frequency - answerit is also known as the critical sampling rate; it
must be at least twice the fastest frequency; if the sample is slower, then aliasing may
occur
Define aliasing - answerwhen the ADC aka analog digital converter samples the analog
signal at a rate LESS than two times its fastest frequency and the analog signal is then
misinterpreted as a slower frequency waveform
What are the Ohm's Law equations? - answerE = I x R. E = voltage
I = E / R. I = current
R = E / I. R = resistance
How many amperes of current will flow in a circuit containg a 2 V battery and 10 ohms
of resistance? - answer0.2 amperes (I)
How many Volts are needed to produce a 20 amp current with a 2 ohm resistance? -
answer40V
Define resistance - answerThe inability of a part of a circuit to allow the passage of
direct (constant voltage) current
Define impedance - answerImpedance is the resistance of a part of a circuit to the
passage of alternating current
Where is the nasion - answera. the indentation between the forehead and the nose
Where is the Inion? - answerthe bony protuberance in the middle of the back of the
head; a ridge or knob that can be felt when you run your finger up the back of the neck
to the skull.
List the standard skull landmarks used in the International 10-20 System. - answerInion,
nasion, L/R preauricular
If the measurement from F8 through Fz to F7 measures 24cm, what are the
measurements to mark F4 and F3 If the zero remains at F8? - answerF8-F4=6cm F8-
F3=18cm
