Equations

Question 1

What is the equation for Boyle’s Law?

Answer 1

PV = K OR V ∝ 1/P

(Pressure, Vol, Konstant)

Question 2

What is Boyle’s law?

Answer 2

If temp of gas is constant then pressure & vol are inversely proportional

Question 3

What is the equation for Charles’ law?

Answer 3

V/T = K OR V∝T
(Vol, Temp, Konstant)

Question 4

What is Charles’ law?

Answer 4

If pressure of a fixed mass of gas is constant then vol & temp are proportional

Question 5

What is Gay-Lussac’s law and what is it also known as?

Answer 5

• Third gas Law
• If the vol of a fixed mass of gas is constant then the pressure & temp are proportional
• Applied to the filling of N2O cylinders

Question 6

What is the equation for Gay-Lussac’s law?

Answer 6

P/T = K OR P∝T

Question 7

How is the filling ratio calculated?

Answer 7

Weight of fluid in cylinder / weight of H2O required to fill cylinder

Question 8

What is Avogadro’s equation?

Answer 8

V/n = K
(Vol, Konstant, amount of substance of gas)

Question 9

What does Avogadro’s equation mean?

Answer 9

Equal volume of gases at same temp & pressure contain same no. of molecules regardless of structure/properties

Question 10

What is the universal gas equation?

Answer 10

PV = nRT
( Pressure, Vol, no. moles of gas, gas constant, temp)

Question 11

What is the universal gas equation a combination of?

Answer 11

Avogadro’s law & Charles’ law

Question 12

What is the equation for Dalton’s law?

Answer 12

P.total = P.gas(a) + P.gas(b)

Question 13

What is Dalton’s law?

Answer 13

In a mixture of gases the total pressure is always equal to the sum of the individual partial pressures of gases.

Question 14

What is Henry’s law?

Answer 14

At constant temp, the mass of a gas that dissolves in a given type & vol of liquid is directly proportional to the partial pressure of that gas in equilibrium with the liquid

Question 15

What is an application of Henry’s law?

Answer 15

• Volatiles: pp of anaesthetic in blood is proportional to pp of anaesthetic in alveoli

Question 16

What’s the equation for Graham’s law of diffusion?

Answer 16

Rate of diffusion = 1 / √MW
(Molecular weight)

Question 17

What is Graham’s law?

Answer 17

• The rate of diffusion of a gas is inversely proportional to the root of a molecular weight
• E.g larger the molecule the slower it diffuses
• Example: 2nd gas effect

Question 18

What is the Hagen- Poiseuille equation?

Answer 18

Q = πPr4 / 8nl
(Flow(Q), pressure, radius, viscosity(n), length)

Question 19

What is the Hagen-Poiseuille principle?

Answer 19

• Characteristics of laminar flow through a tube
• As pressure differential along tube increases so does flow.
• Only applies to Newtonian fluids

Question 20

What is the equation for Reynold’s number?

Answer 20

Re = pvd / n
(density, velocity, diameter, viscosity(n))

Question 21

What does Reynold’s number describe?

Answer 21

Factors that determine the critical velocity when flow becomes turbulent

Question 22

What is the equation for Laplace’s law?

Answer 22

T = PR / 2t. OR P = T / R
(Tension, pressure gradient, radius, wall thickness(t))

Question 23

What does Laplace’s law explain?

Answer 23

As the radius of a tube/sphere increases the pressure gradient decreases but as surface tension increases the pressure increases

Question 24

What is Bernoulli’s equation?

Answer 24

P + 0.5pv2 + pgh = constant

(Pressure(P), density(p), velocity, acceleration(g), height)

Question 25

What is entrainment ratio?

Answer 25

ER = Entrained flow / driving flow

Question 26

What's the equation for Ohm's law?

Answer 26

V = IR (voltage, current, resistance)

Question 27

What does Ohm's law state?

Answer 27

The electrical current is directly proportional to the potential difference applied.

Question 28

How is capacitance calculated?

Answer 28

F = C/V (Farad/capacitance, Coulomb, Voltage)

Question 29

What is the equation for inductance?

Answer 29

H = Wb / A (Inductance, Weber/magnetic field, amp)

Question 30

What is the equation for work done?

Answer 30

W = F x D (Work, Force, distance)

Question 31

How is charge calculated?

Answer 31

Q = I x T. or Q = C x V (Charge, Current, Time) or (Charge, capacitance, voltage)

Question 32

What is the Beer-Lambert equation?

Answer 32

A = ɛdc (Absorbance, extinction coefficient(ɛ), path length, conc)

Question 33

What is the Beer-Lambert Law?

Answer 33

- The transmission of light through a substance is inversely proportional to its molar conc & thickness

Question 34

What is the equation for natural frequency?

Answer 34

NFa D/√LCd (natural frequency, catheter diameter, length, compliance, density)

Question 35

What is the wave equation?

Answer 35

V = f x λ (Velocity, frequency, wavelength)

Question 36

What is the equation for volume of distribution?

Answer 36

Vd = X / C (Vol, Amount of drug, plasma conc)

Question 37

What is the equation for clearance?

Answer 37

Cl = K x Vd (Clearance, rate constant, vol of distribution)

Question 38

How is O2 delivery calculated?

Answer 38

Delivery = FiO2 x MV

Question 39

How is O2 content calculated?

Answer 39

CaO2 = Hb x Sats x 1.34 + PaO2 x 0.023 Content = amount in plasma + amount bound to Hb

Question 40

How is the amount of O2 bound to Hb calculated?

Answer 40

Hb x Sats x Hüfners constant (1.34)

Question 41

What is the alveolar gas equation?

Answer 41

PaO2 = FiO2(P.at - P.H2O) - PaCO2/0.8

Question 42

How is rate of elimination calculated?

Answer 42

Conc x clearance

Question 43

How is vol of distribution calculated?

Answer 43

Vd = Dose / Conc

Question 44

How is 1/2 life calculated?

Answer 44

half life = 0.69 x time constant

Question 45

How is elimination rate constant calculated?

Answer 45

K = 1/ time constant

Question 46

How is clearance calculated?

Answer 46

Clearance = Vd x K

Question 47

How is loading dose calculated?

Answer 47

LD = Vd x target conc

Question 48

How is maintenance infusion rate calculated?

Answer 48

Rate = target conc x clearance