SEMMELWEIS UNIVERSITY,
MEDICAL BIOPHYSICS - Exam
Study Guide – Practice
Questions with Verified
Answers. GRADED A+. Latest
2026/2027 Update
Coulter principle. - 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 - 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)
,- 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? - 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? - 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? - Answer ✔✔
<<<<<💕💕💕✔✔By integral discrimination (the size of the platelets
is much smaller)
What is the role of differential discriminator in Coulter-counting? - Answer
✔✔Mapping the size distribution of the particle
,Why is dilution of blood is necessary in Coulter-counting? - Answer ✔✔
<<<<<💕💕💕✔✔Because the cells themselves do not conduct well, and so we
dilute them with an electrolyte solution so changes in resistivity are noticed. Also,
for practical reasons (e.g. we don't want the solution to dry up.)
What solution is used for blood dilution in Coulter-counting? - Answer ✔✔
<<<<<💕💕💕✔✔Saline solution, for optimal osmotic pressure (keep the RBCs
in their natural size) and for good conduction (NaCl)
How does the matter flow density (flux) change if the concentration gradient is
doubled? - Answer ✔✔It doubles, due to flicks first law: Jv=-Dxdeltac/deltax
Name the parameters influencing the value of diffusion coefficient. - Answer ✔✔
<<<<<💕💕💕✔✔Size and shape of the particle as well as the temperature and
viscosity of the medium. Can be calculated for spherical particles: D=kT/6 pi n r
What diffuses faster: a potassium ion or a virus particle? - Answer ✔✔K+ ion due
to smaller diffusion coefficient (smaller size)
How does the average distance travelled by a diffusing particle depend on time? -
Answer ✔✔Square root function (Distance average ^2 =6 * D * t)
On what length scale is diffusion an effective transport process? - Answer ✔✔
<<<<<💕💕💕✔✔On a small scale
, How does the minimum wavelength of the x-ray spectrum change with increasing
anode voltage? - Answer ✔✔Decreases (higher voltage higher kinetic energy
higher frequency spectrum) - Duane-hunt law
How does the minimum wavelength of the x-ray spectrum change with increasing
anode current? - Answer ✔✔Does not change
What is the maximum x-ray photon energy at 50 kV anode voltage? - Answer ✔✔
<<<<<💕💕💕✔✔50 keV
What elements are suitable as x-ray-tube anode material? - Answer ✔✔High
melting point and high atomic number materials molybdenum
(more common in medical diagnosis) and tungsten.
What are the x-ray spectral lines characteristic of? - Answer ✔✔Anode material
Why do we need to cool the x-ray-tube anode? - Answer ✔✔Because it heats up
due to low efficiency in the conversion of high kinetic energy to x-ray.
How does x-ray absorbance depend on the atomic number of
absorber? - Answer ✔✔Photo Effect is the dominant attenuation process:
photoeffect = micro m - Z^3
Which part of the x-ray spectrum is attenuated by filtering? - Answer ✔✔The long
wavelengths (to avoid unnecessary radiation absorption, these photons and may
hurt resolution due to scattering)
MEDICAL BIOPHYSICS - Exam
Study Guide – Practice
Questions with Verified
Answers. GRADED A+. Latest
2026/2027 Update
Coulter principle. - 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 - 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)
,- 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? - 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? - 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? - Answer ✔✔
<<<<<💕💕💕✔✔By integral discrimination (the size of the platelets
is much smaller)
What is the role of differential discriminator in Coulter-counting? - Answer
✔✔Mapping the size distribution of the particle
,Why is dilution of blood is necessary in Coulter-counting? - Answer ✔✔
<<<<<💕💕💕✔✔Because the cells themselves do not conduct well, and so we
dilute them with an electrolyte solution so changes in resistivity are noticed. Also,
for practical reasons (e.g. we don't want the solution to dry up.)
What solution is used for blood dilution in Coulter-counting? - Answer ✔✔
<<<<<💕💕💕✔✔Saline solution, for optimal osmotic pressure (keep the RBCs
in their natural size) and for good conduction (NaCl)
How does the matter flow density (flux) change if the concentration gradient is
doubled? - Answer ✔✔It doubles, due to flicks first law: Jv=-Dxdeltac/deltax
Name the parameters influencing the value of diffusion coefficient. - Answer ✔✔
<<<<<💕💕💕✔✔Size and shape of the particle as well as the temperature and
viscosity of the medium. Can be calculated for spherical particles: D=kT/6 pi n r
What diffuses faster: a potassium ion or a virus particle? - Answer ✔✔K+ ion due
to smaller diffusion coefficient (smaller size)
How does the average distance travelled by a diffusing particle depend on time? -
Answer ✔✔Square root function (Distance average ^2 =6 * D * t)
On what length scale is diffusion an effective transport process? - Answer ✔✔
<<<<<💕💕💕✔✔On a small scale
, How does the minimum wavelength of the x-ray spectrum change with increasing
anode voltage? - Answer ✔✔Decreases (higher voltage higher kinetic energy
higher frequency spectrum) - Duane-hunt law
How does the minimum wavelength of the x-ray spectrum change with increasing
anode current? - Answer ✔✔Does not change
What is the maximum x-ray photon energy at 50 kV anode voltage? - Answer ✔✔
<<<<<💕💕💕✔✔50 keV
What elements are suitable as x-ray-tube anode material? - Answer ✔✔High
melting point and high atomic number materials molybdenum
(more common in medical diagnosis) and tungsten.
What are the x-ray spectral lines characteristic of? - Answer ✔✔Anode material
Why do we need to cool the x-ray-tube anode? - Answer ✔✔Because it heats up
due to low efficiency in the conversion of high kinetic energy to x-ray.
How does x-ray absorbance depend on the atomic number of
absorber? - Answer ✔✔Photo Effect is the dominant attenuation process:
photoeffect = micro m - Z^3
Which part of the x-ray spectrum is attenuated by filtering? - Answer ✔✔The long
wavelengths (to avoid unnecessary radiation absorption, these photons and may
hurt resolution due to scattering)
