SEMMELWEIS UNIVERSITY, Medical
Biophysics II. Final - Practice Exam 2026
Questions and Answers
Coulter principle. - Correct Answer-The ability to count and measure the size of
particles using an electric circuit. Particles are moved through a small aperture,
their presence causes a narrowing of the aperture, which leads to an increase in
resistance.By using constant I, According to Ohms law (U= I * R), when R
increases, U increases and pulse is generated.
Parts and functions of the Coulter-counter - Correct Answer-- Two spaces with a
small aperture in between, capillary (contains the electrolyte solution with the
cells)
- Measuring electrode, one in each of the spaces (closing the circuit and measuring
voltage between the two spaces)
- Pump (draws the solution into the smaller space, and out
again, through the capillary)
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, - Auxiliary electrode (signals when certain volume is
reached, to initiate pumping out of the solution)
- Integral Discriminator (filter out noise)
- Differential Discriminator (mapped of the size distribution
of the particles)
How does the voltage pulse amplitude depend on particle size in the Coulter-
counter? - Correct Answer-Its proportional, bigger particle will form higher
resistance, higher voltage pulse.
How do you separate the red-blood-cell versus white-blood-cell signals in a
Coulter-counter? - Correct Answer-when you want to measure RBC, it's not
necessary to separate them from the RBC b.c. the number of WBC is negligible
(less than error of the measurement)
By hemolyze RBC and measured them separately photochemically and subtracted
the result from the coulter-counting measurement
How do you separate the red-blood-cell versus platelet signals in a Coulter-
counter? - Correct Answer-By integral discrimination (the size of the platelets is
much
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
Biophysics II. Final - Practice Exam 2026
Questions and Answers
Coulter principle. - Correct Answer-The ability to count and measure the size of
particles using an electric circuit. Particles are moved through a small aperture,
their presence causes a narrowing of the aperture, which leads to an increase in
resistance.By using constant I, According to Ohms law (U= I * R), when R
increases, U increases and pulse is generated.
Parts and functions of the Coulter-counter - Correct Answer-- Two spaces with a
small aperture in between, capillary (contains the electrolyte solution with the
cells)
- Measuring electrode, one in each of the spaces (closing the circuit and measuring
voltage between the two spaces)
- Pump (draws the solution into the smaller space, and out
again, through the capillary)
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
, - Auxiliary electrode (signals when certain volume is
reached, to initiate pumping out of the solution)
- Integral Discriminator (filter out noise)
- Differential Discriminator (mapped of the size distribution
of the particles)
How does the voltage pulse amplitude depend on particle size in the Coulter-
counter? - Correct Answer-Its proportional, bigger particle will form higher
resistance, higher voltage pulse.
How do you separate the red-blood-cell versus white-blood-cell signals in a
Coulter-counter? - Correct Answer-when you want to measure RBC, it's not
necessary to separate them from the RBC b.c. the number of WBC is negligible
(less than error of the measurement)
By hemolyze RBC and measured them separately photochemically and subtracted
the result from the coulter-counting measurement
How do you separate the red-blood-cell versus platelet signals in a Coulter-
counter? - Correct Answer-By integral discrimination (the size of the platelets is
much
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
