FRCA Equations

Question 1

Equation for Ohm’s law

Answer 1

V = I.R

Question 2

Equation for power (electrical)

Answer 2

Power(W) = VI = I^2.R

Question 3

Equation for charge (electrical)

Answer 3

Q(Coulombs) = I.t (Amps*Seconds)

Question 4

Equation for capacitance (electrical)

Answer 4

C (farads) = Q / V

Question 5

Equation for stored energy (defibrillator)

Answer 5

E (Joules) = 1/2.C.V^2 = 1/2.Q.V

Question 6

Equation for resistors in series (electrical)

Answer 6

R total = R1 + R2 + R3 …

Question 7

Equation for resistors in parallel (electrical)

Answer 7

1/R total = 1/R1 + 1/R2 + 1/R3 …

Question 8

Equation for Bioavailability

Answer 8

Bioavailability = AUC oral / AUC IV (where AUC is area under time-concentration curve)

Question 9

Value for ‘e’ (Euler’s number)

Answer 9

2.718…

Question 10

Value for 1/e

Answer 10

0.37…

Question 11

Equation for a differential equation of a concentration-time curve (i.e. change in concentration over time)

Answer 11

dC/dt ∝ C

Question 12

Equation for a concentration with a negative exponential relationship

Answer 12

dC/dt = -kC
so…
C(t) = C0.e^-kt

Where C=concentration, C0=conc@time0, t=time, k=rate constant

Question 13

Equation for dissociation constant

Answer 13

KD=[D][R]/[DR]

Where D=free drug, R=unoccupied receptors, DR=drug occupied receptors

Question 14

Laminar flow - Hagen-Poiseuille Equation

Answer 14

Q = π.P.r^4 / 8.η.l
OR
Q = π.P.d^4 / 128.η.l
OR
P = Q.(8.η.l / π.P.r^4)

Where Q=flow, P=change in pressure, r=radius, d=diameter, η=viscosity, l=length

Question 15

Reynolds Number

Answer 15

Dimensionless number predicting fluid flow pattern (i.e. laminar vs turbulent)

= v.p.d / η

Where v=fluid velocity, p=change in pressure, d=diameter, η=viscosity

Question 16

Turbulent flow

Answer 16

Q ∝ √P
Q ∝ 1/√l
Q ∝ 1/√p

Q=flow, P=change in pressure, l=length, p=density

Question 17

Bernoulli’s Equation

Answer 17

1/2.p.v^2 + P (+pgh) = K

p=density, v=velocity, P=static pressure of fluid at cross section, g=gravity, h=height

Question 18

Absolute humidity

Answer 18

The mass of water (grams) per volume of air (m^3)

Question 19

Relative humidity

Answer 19

Relative humidity = actual vapour pressure / saturated vapour pressure

The ratio of water vapour present in air relative to the maximum possible for a given temperature.

(ratio of the partial pressure of water vapour in the mixture to the equilibrium vapour pressure of water over a flat surface of pure water at a given temperature)

Question 20

Equation for affinity

Answer 20

Affinity = 1 / KD

Question 21

Equation for enzyme kinetics

Answer 21

V = Vmax.[S] / Km + [S]

V = initial velocity; Vmax = maximum initial velocity; Km = concentration at which the initial velocity is half the maximal initial velocity; S = substrate

Question 22

Volume of distribution equation

Answer 22

Vd = D / C0

Vd = volume of distribution; D = dose; C0 = concentration at time zero.

Question 23

Pharmacokinetic time constant and half time equations

Answer 23

T = 1 / Kel

T = Vd / Cl

t1/2 = T.loge(2)

T = time constant; Kel = rate of elimination; Vd = volume of distribution; Cl = clearance.

Question 24

Loading dose and maintenance dose equations

Answer 24

Loading dose = Vd.Cp

Maintenance dose = Cp.Cl

Vd = volume of distribution; Cp = plasma concentration; Cl = clearance.

Question 25

Three compartment model equation

Answer 25

Cp = A.e^-at + G.e^-gt + B.e-bt

Question 26

Equations for pressure

Answer 26

Pressure (Pa) = force (N) / area (m2)

Absolute pressure = gauge pressure + atmospheric pressure

Question 27

Ideal gas laws

Answer 27

P.V = K (Boyles)

V / T = K (Charles)

P / T = K (Gay Lussac / 3rd)

P.V / T = K

P.V = n.R.T

P = pressure; V = volume; T = temperature (K); n = number of moles; R = universal gas constant.

Question 28

Energy equations:
Kinetic, Potential, Electrical, Metabolic energy content, Specific heat capacity

Answer 28

KE = 1/2.m.v^2
PE = m.g.h
EE = I.V.s
Met energy - multiply energy content per mass by the mass
SHC - Energy per mass per degree of temperature

Question 29

Tension: tube and sphere

Answer 29

Tube: P = T / r
Sphere: P = 2T / r

P = pressure gradient; T = tension; r = radius.

Question 30

Work

Answer 30

Work = force * distance
J = N.m = kg.m^2 / s^2

Question 31

Linear function

Answer 31

y = Mx + c

M = gradient of straight line
c = y axis intercept

Question 32

Lambert- Bouguer law

Beer-Lambert law

Answer 32

I = I0.e^-ad

I = transmitted light; I0 = incident light; a = extinction coefficient for the solution; d = thickness.

Absorbance = ε.c.d

ε = molar extinction coefficient; c = molar concentration; d = thickness

Question 33

Variance - standard deviation equation

Standard error of the mean

Answer 33

SD = Σ(x-x̄)^2 / (n-1)

SE = SD / √ (n-1)

Question 34

Rate of diffusion

Answer 34

Q = Kp.A/T.(C1-C2)

Q = rate of diffusion; Kp = permeability constant (proportional to solubility over molecular weight); A = area of membrane; T = thickness of membrane; C1-C2 = concentration gradient

Question 35

Osmotic pressure

Answer 35

π = RTC

π = osmotic pressure; R = universal gas constant; T = absolute temperature; C = osmolality (mosm/kgH20

Question 35

Measurement of fluid compartments

Answer 35

Compartment volume = mass of indicator / concentration in compartment

Question 36

Plasma osmolality

Answer 36

mosm/kgH20 = 2[Na] + [glucose] + [urea]