Cardiff Q - Physics

Question 1

‘Ideal gas’ 3 principles

Answer 1

Molecules so far apart there are no attractive forces between them

Volume of molecules themselves are negligible

Molecules are in random motion and obey Newton’s laws of motion

Question 2

Dalton’s law definition and equation

Answer 2

Total pressure of a gas mixture is the sum of all its individual gas pressures

Pt = P1 + P2 + P3 ….

Question 3

Boyle’s law

Answer 3

For a fixed amount of gas at a constant temperature, the volume is inversely proportional to its pressure

P proportional 1 / V

Question 4

Charles’ law

Answer 4

At a constant pressure, volume is directly proportional to temperature

Question 5

Gay-Lussac’s law

Answer 5

At a constant volume, pressure is directly proportional to its temperature.

Question 6

Combined gas law

Answer 6

P1 x V1 / T1 = P2 x V2 / T2

Question 7

Universal gas law

Answer 7

PV = nRT

n = number of moles
R = universal gas constant

Question 8

Henry’s law

Answer 8

At a constant temperature, the amount of gas dissolved in a liquid is directly proportional to the partial pressure of a gas in equilibrium with it

Question 9

Vapour definition

Answer 9

Gas below its critical temperature

Question 10

Latent heat of vapourisation

Answer 10

As vapour molecules picked up by gas flow, resultant vapour liquid cools

Therefore need to maintain temperature as otherwise properties of gas changes (as described in the gas laws)

Question 11

Mechanism to maintain safe and variable volatile agent use

Answer 11

Bypass channel with splitting ratio modifiable via dial

Question 12

Desfluorane approximate boiling point

Answer 12

Boiling point very close to room temperature

Question 13

Ohms law

Answer 13

Voltage = Current x Resistance
V=IR

Question 14

Approximate resistance of Humans

Answer 14

~ 1500 Ohm

Reduced when wet

Question 15

What causes damage to tissue from electrocution

Answer 15

Electrical current
Higher current, higher damage

Question 16

Consideration for severity of shock

Answer 16

Voltage of source
Resistance of body
Timing of shock - eg cardiac rhythm

Question 17

Electrocution symptoms at 1mA

Answer 17

Tingling sensation

Question 18

Electrocution symptoms at 5mA

Answer 18

Threshold for “harmless” current

Question 19

Electrocution symptoms at 10-20 mA

Answer 19

Sustained muscular contraction
‘Can’t let go’ threshold as flexors stronger than extensors in upper limbs

Question 20

Electrocution symptoms at 100-300 mA

Answer 20

Ventricular fibrillation

Question 21

Electrocution symptoms at 6A

Answer 21

Respiratory paralysis and burns

Question 22

Microshocks

Answer 22

Unintended flow of small (but dangerous) currents directly or close proximity to the heart

Bypasses highly resistant skin barrier

Eg central lines, pacing wires

Question 23

Electrical safety devices / features

Answer 23

Earthing

Isolated systems

Wire insulation

Fuse

Circuit breakers

Residual current device (RCD)

Question 24

Isolated electrical systems

Answer 24

Uses an isolating transformer to isolate the equipment from the mains power supply

Question 25

Fuse

Answer 25

Thin wire which melts when certain current reached

Question 26

Circuit breaker

Answer 26

Similar concept to fuse but uses electromagnets

Question 27

Classification of electrical equipment

Answer 27

Class 1
Class 2
Class 3

Question 28

Class 1 electrical equipment

Answer 28

The casing of the equipment must be earthed

Question 29

Class 2 electrical equipment

Answer 29

Equipment is double insulated so does not require earthing

Question 30

Class 3 electrical equipment

Answer 30

Separated extra low voltage circuit using isolating transformer
No earthing required

Question 31

Classification of leakage current based on use of equipment

Answer 31

Type B
Type BF
Type CF

Question 32

Type B leakage current equipment

Answer 32

Contact with body only

Max leakage current 0.1 mA
Can be class 1,2 or 3

Question 33

Type BF leakage current equipment

Answer 33

Contact with body only. Isolated from mains (hence F for floating)

Max leak 0.1 mA

Class 3 equipment only

Question 34

Type CF leakage current equipment

Answer 34

For cardiac equipment

Missed info from this slide so look up the gaps here ……