CNIM Instrumentation Exam Questions
with 100% Correct Answers
When using constant voltage for racial nerve stim and the nerve becomes bathed in
CSF, what will occur after the area is suctioned... - Answer- The current flow will very in
order to maintain the preset voltage level
Reduction of the high frequency filter... - Answer- Increases EP latency
The sensitivity setting on an amplifier set to produce a vertical deflection of 1 cm with an
input of 10 mV is... - Answer- I cm = 10 mm
1 mV/mm
Prestimulus Triggering... - Answer- Includes a period of recording before the stimulus
Given an electrical circuit with a resistance of 1000 ohms and a voltage of 10 volts, the
current flow will be... - Answer- V = IR
I = V/R
I = 10 V/ 1000 ohms = 0.01 A
If you have a signal to noise ratio of 1:2, averaging 64 responses will... - Answer-
Square root of 64 = 8
8:2 = 4:1
Capacitors are electronic devices used to... - Answer- Store electrical energy
With a sampling rate of 10 kHz, the shortest sign wave resolved would be... - Answer-
0.2 msec?
Hz = revolution/sec
The phenomenon called "aliasing" - Answer- Refers to an erroneous representation of
an analog signal by digital values
Signal-to-noise ratio relates to what? - Answer- The amplitude of the evoked response
components to the amplitude of the unrelated components.
If you have a small signal with a lot of noise, what should you do to help resolve your
signal? - Answer- Increase your averages
If you have a 5 uV signal amplitude and a 20 uV noise amplitude, how many averages
would you need to get a signal to noise ratio of 2:1? - Answer- SNRi = 1:4
, Noise needs to be 8 to be 2:1
Averages = 64
During electrocautery we should... - Answer- Pause recording
The gain of a differential amplifier is defined as... - Answer- Output voltage divided by
input voltage
The positive input of a differential amplifier is also called the... - Answer- Non-inverting
input
If you get artifact in your subcortical channel you... - Answer- Use a spare Cs5 electrode
The minimum required Common Mode Rejection Ratio of a differential amplifier is... -
Answer- 10,000:1
A differential amplifier with a gain of 1,000,000 has a 0.2 uV signal at its positive input
and a 0.8 uV signal at its negative input. The output will be... - Answer- A downward
peak of 0.6 V
A 10 Hz signal passing through a 10 Hz locut filters will be: - Answer- Reduced in
amplitude by approximately 30%
A major advantage of digital filters over analog filters is... - Answer- They impose no
phase effects on the recorded signal
Lowering the SSEP hi-cut filter from 500 Hz to 200 Hz may cause cortical peaks to
appear... - Answer- Longer in latency
What time constant would be most effective for cutting out low frequency noise from
your signal? - Answer- 10 ms
What is the required horizontal resolution of an EP system? - Answer- 20 uS per data
point or less
The vertical resolution of an EP system depends primarily on,,, - Answer- The number
of bits in the A/D converter
A unit of resistance is symbolized by... - Answer- Ohms
Fast Fourier transformation - Answer- The mathematical transformation f a complex
waveform into simpler, more uniform waves
The capacity to resolve amplitudes of 256 discrete steps would require an 8 bit A to D
converter. This can be represented by... - Answer- 2^8
with 100% Correct Answers
When using constant voltage for racial nerve stim and the nerve becomes bathed in
CSF, what will occur after the area is suctioned... - Answer- The current flow will very in
order to maintain the preset voltage level
Reduction of the high frequency filter... - Answer- Increases EP latency
The sensitivity setting on an amplifier set to produce a vertical deflection of 1 cm with an
input of 10 mV is... - Answer- I cm = 10 mm
1 mV/mm
Prestimulus Triggering... - Answer- Includes a period of recording before the stimulus
Given an electrical circuit with a resistance of 1000 ohms and a voltage of 10 volts, the
current flow will be... - Answer- V = IR
I = V/R
I = 10 V/ 1000 ohms = 0.01 A
If you have a signal to noise ratio of 1:2, averaging 64 responses will... - Answer-
Square root of 64 = 8
8:2 = 4:1
Capacitors are electronic devices used to... - Answer- Store electrical energy
With a sampling rate of 10 kHz, the shortest sign wave resolved would be... - Answer-
0.2 msec?
Hz = revolution/sec
The phenomenon called "aliasing" - Answer- Refers to an erroneous representation of
an analog signal by digital values
Signal-to-noise ratio relates to what? - Answer- The amplitude of the evoked response
components to the amplitude of the unrelated components.
If you have a small signal with a lot of noise, what should you do to help resolve your
signal? - Answer- Increase your averages
If you have a 5 uV signal amplitude and a 20 uV noise amplitude, how many averages
would you need to get a signal to noise ratio of 2:1? - Answer- SNRi = 1:4
, Noise needs to be 8 to be 2:1
Averages = 64
During electrocautery we should... - Answer- Pause recording
The gain of a differential amplifier is defined as... - Answer- Output voltage divided by
input voltage
The positive input of a differential amplifier is also called the... - Answer- Non-inverting
input
If you get artifact in your subcortical channel you... - Answer- Use a spare Cs5 electrode
The minimum required Common Mode Rejection Ratio of a differential amplifier is... -
Answer- 10,000:1
A differential amplifier with a gain of 1,000,000 has a 0.2 uV signal at its positive input
and a 0.8 uV signal at its negative input. The output will be... - Answer- A downward
peak of 0.6 V
A 10 Hz signal passing through a 10 Hz locut filters will be: - Answer- Reduced in
amplitude by approximately 30%
A major advantage of digital filters over analog filters is... - Answer- They impose no
phase effects on the recorded signal
Lowering the SSEP hi-cut filter from 500 Hz to 200 Hz may cause cortical peaks to
appear... - Answer- Longer in latency
What time constant would be most effective for cutting out low frequency noise from
your signal? - Answer- 10 ms
What is the required horizontal resolution of an EP system? - Answer- 20 uS per data
point or less
The vertical resolution of an EP system depends primarily on,,, - Answer- The number
of bits in the A/D converter
A unit of resistance is symbolized by... - Answer- Ohms
Fast Fourier transformation - Answer- The mathematical transformation f a complex
waveform into simpler, more uniform waves
The capacity to resolve amplitudes of 256 discrete steps would require an 8 bit A to D
converter. This can be represented by... - Answer- 2^8
