Biophysique > Practical Exam > Flashcards

Practical Exam Flashcards

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1
Q

Density def:

A

Property indicating how much substance is in unit of volume

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2
Q

Density formula:

A

p = m/V (mass, volume) kg/m^3

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3
Q

Density SI

A

Kg/m^3

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4
Q

Density depends on

A

Temperature, mass, crystalline form
If T goes up p goes down, exception for water

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5
Q

Density of heterogenous

A

p(r) = dm(r)/dV(r)

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6
Q

Relative density of liquid

A

p = p(liquid)/p(solution)

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7
Q

Measuring density of liquids (material)

A
  • scale
  • pipette
  • pycnometer
  • distilled water
  • solution sample
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8
Q

Density of liquids procedure

A
  • weigh empty pycnometer
  • fill with water and weigh
  • fill with sample and weigh
  • find pycnometer volume
  • calculate density
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9
Q

Density of solids material

A
  • scale
  • pycnometer
  • solid
  • distilled water
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10
Q

Density of solids procedure

A
  • weight solid in air
  • fill pycnometer with water znd weigh
  • fill water pycnometer with solids and weigh
  • calculate
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11
Q

What is measurement of density of solids by immersion technique based on

A

Archimeds law: a solid is lighter in water than in air

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12
Q

Buoyant force formula

A

Fb = mH2O x g

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13
Q

Density of solids by immersion material

A
  • scale
  • beaker
  • water
  • sample
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14
Q

Density of solids by immersion procedure

A
  • weight sample in air
  • weight sample immersed in water
  • calculate
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15
Q

Order of magnitude

A

Approximating answer

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16
Q

Fluids definition

A

Substance that can flow, given by velocity of particles per time

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17
Q

Flaw rate through pipe

A

Quantity of fluid passing through cross section of pipe in unite time

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18
Q

Volumetric flow rate

A

Qv = delta V /delta t
SI = m^3/s

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19
Q

Mass flow rate

A

Qm = delta m / delta t
SI: kg/s

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20
Q

Relation btw mass flow rate and voluletric flow rate

A

Qm = p x Qv

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21
Q

Laminar or streamline flow

A
  • liquid flows smooth
  • parallel layers to direction of flow
  • low energy consume
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22
Q

Turbulent flow

A
  • molecular flow irregulzr
  • generate currents
  • high energy consumption for flow rate
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23
Q

Viscosity def

A

Resistance to flow

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24
Q

Viscosity determinced by

A
  • internal frictions btw layers of fluid
  • determined by size of molecules
  • more temperature leads to lower viscosity
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25
Motion of liquid newtonian law
F = nxAx(delta Vx / delta y)
26
Constant of proportionality n
- represents dynamic viscosity of liquid - SI: (N x s)/m^2 = Pa x s
27
Newtonian fluids
If dynamic viscosity of fluid depends on velocity, liquids are non newtonian like blood
28
Flow rate through cylindrr formula
Qv = delta (p . pi . r^4)/(8.n.L)
29
What does the nature of flow depend on
Reynold's number Re = (p.v.r).n Re < 2000 -> laminer Re > 4000 -> turbulent Also there is in between
30
Buoyancy force
Weight of didplaced Volume of liquid Fb = (4.pi.r^2)/3 .p.g
31
Instrument for viscosity
Ostwald viscosmeter n(solution) = n(h20).(ps/ph2o).(ts/th2o)
32
Hoppler viscometer
- fill with water - put solide in tube - wait for it to go from line 1 to line 2 and record time - do the same with other liquids - calculate
33
What keeps molecules packed together
Intermoleculzr interactions, cohesive forces
34
What is internal pressure
The molecules at surface in contact with air are attracted inwars creating pressure
35
Potential energy of surface layer
Ep = surface tension x A
36
Surface tension
Represents the surface energy per unit area SI: J/m^2 = N/m
37
Tensioactive substance
Substance that are absorbed in surface layer and reduce surface tension
38
Stalagmometer, drop counting method
- fill stalafmometer with water, count drops, use a solution with diff concentration after, determine surface tension for solution
39
Enthalpy formula
H = U + pV U = internl energy P = pressure V = volume
40
Enthalpy variation formula
delta H = delta U + p x delta V
41
Enthalpy variation def
Heat released or absorbed by the system in isobaric process
42
Why use calorimeter
So the energy will be conserved deltaQ...
43
Determination of dissolution enthalpy procedure
Fill calorimeter with some water, measure temperature, put kcl in tube and put tube in calorimeter, meadure temp, put tube contents in calorimeter, measure temp
44
Determination of enthalpy formula
delta Q = delta H = -(m.c+C).delta T
45
Heat definition
Form of energy describing energetic exchange between a thermodynamic system and surrounding environment
46
Heat capacity
Amount of heat necessary to change temperature of substance by 1°C C = deltaQ/deltaT
47
Specific heat capacity
Quantity of heat necessary for unit mass of substance to change by 1°C c = 1/m . deltaQ/deltaT
48
Molar heat capacity
Quantity of heat necessary for mole of substance to change temperature by 1 degree Cmolar = 1/n . deltaQ/deltaT delta Q is heat exchanges with surrounding Delta T is température variation
49
Heat in SI
Joules J
50
Calorie def
Amount of heat required to rise teperzture of one gram of water
51
C (Heat capacity) SI
C = deltaQ/deltaT 1.J/K
52
c (specific heat) SI
c = 1/m. deltaQ/deltaT J/(kg.K)
53
Cmolar (molar heat) SI
Cmolar = deltaQ/(n.deltaT) J/mole.K
54
Latent heat
Specific heat at phase transition, heat exchange with no temperature change J/kg
55
Determination of specific heat of solids
- weight metals, fill water in cup and heat to 100 degrees with metals inside, put water in calorimeter and record temp, put metal in calorimeter and record temperature when equilibrium, use formulas
56
Refractive index
Ratio between speed of light in vacuum and in material n = c/v Shows how much the speed of light is reduced when passing through optical transparent
57
Reflection of light
Partial or total return of light
58
Refraction of light
Abrupt change in direction of propagation as it passes from one optical medium to another
59
Snell's law
Sin i /sin r =n2/n1 =n21 n21 = relative reftractive index
60
Optical lenses
Refracting devices
61
Focal point of lens
Point where parallel rays incident upon the lens converge
62
How many focal points does lens have
2, object and image
63
Convergence power
Reciprocal of focal length, C=1/f SI: diopter = 1m^-1
64
Magnification of a lens
B =y2/y1
65
Optical aberration
Distortion of optical images, caused by shape of lens and wave of light
66
Types of aberration
Spherical,coma,chromatic,distortion
67
Focal distance
1/x2-1/x1=1/f
68
Optical microscope
Optical instrument, objective,eyepiece,condenser
69
Magnification
Ratio between tangent of angle under which one can see image thru instrument and tangent of zngle once can see when looked at with naked eye G = tg a'/tg a
70
Resolution
Shortest distance between two points of specimen d = (0,61 . lambda)/NA NA = numerical aparture
Biophysique
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