# Chapter 4a – Physics Questions

## Abstract

Physics Questions

## Chapter 4a Physics Questions

### Question 1

Which of the following statements regarding SI units are correct?

1. a. SI stands for ‘Standard Indices’

2. b. There are seven SI base units

3. c. SI base units include current, temperature and luminance

4. d. Frequency is a base SI unit and is measured in hertz (Hz)

5. e. Force is a derived SI unit and is measured in newtons (kg.m.s−2)

### Question 2

Which of the following SI definitions are correct?

1. a. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon-14

2. b. The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second

3. c. A watt is the energy expended when the point of application of a force of 1 newton moves 1 metre in the direction of the force

4. d. A joule is a measurement of the rate of energy expenditure (power). 1 joule is 1 watt per second

5. e. A pascal is the pressure of 1 newton per square metre

### Question 3

The following are exact equivalents to 1 atmosphere of pressure:

1. a. 1.013 bar

2. b. 101.33 Pa

3. c. 760 mmHg

4. d. 760 Torr

5. e. 9 898 043 cmH2O

### Question 4

Regarding heat and temperature:

1. a. A kelvin is defined as 1/273.16 of the thermodynamic temperature of the triple point of water

2. b. The triple point of water is the temperature and pressure at which its three different phases are in equilibrium

3. c. The triple point of water occurs at 100 oC

4. d. Temperature (K) is equal to temperature (°C) + 273.16

5. e. Heat capacity is defined as the quantity of heat required to raise the temperature of an object by 1/273.16 K

### Question 5

Regarding techniques of temperature measurement:

1. a. All four of these are techniques used in hospital practice: the bimetallic strip, the resistance thermometer, the thermistor and the thermocouple

2. b. The bimetallic strip utilizes the generation of a small voltage at the junction of two dissimilar metals, the magnitude of which is dependent on the temperature at the junction

3. c. In a resistance thermometer, the electrical resistance increases exponentially with temperature

4. d. In a thermistor, the electrical resistance decreases exponentially with temperature

5. e. The thermocouple utilizes the Seebeck effect to measure temperature

### Question 6

Consider the following statements regarding heat production and loss:

1. a. In man, body temperature is normally regulated to 34 ± 0.5 oC

2. b. Children up to the age of 12 utilize brown fat for thermogenesis

3. c. Radiation typically contributes the majority of heat loss

4. d. Respiration typically contributes 30% of heat loss

5. e. Convection typically contributes 20% of heat loss

### Question 7

Which of the following statements regarding latent heat are correct?

1. a. The change in heat required to change a vapour to a liquid is known as the latent heat of vaporization

2. b. The latent heat of vaporization of a gas is zero at its critical temperature

3. c. When in use, the pressure gauge reading on a nitrous oxide cylinder will always be accurate

4. d. The critical temperature of oxygen is –119 oC

5. e. The critical temperature of nitrous oxide is –36.5 oC

### Question 8

Which of the following statements regarding gas laws are correct:

1. a. Boyle’s law describes that at a constant temperature, the volume of gaseous oxygen in a cylinder varies inversely with gauge pressure

2. b. Charles’ law states that at constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature

3. c. Gay-Lussac’s law states that at a constant volume, the absolute pressure of a fixed mass of gas is directly proportional to its temperature

4. d. The standard temperature used is 273.15 K

5. e. The standard pressure used is 760 mmHg

### Question 9

An ‘ideal gas’ is a theoretical concept. Which of the following are true regarding ideal gases?

1. a. Collisions never result in loss of kinetic energy

2. b. Van der Waals’ forces exist between molecules

3. c. The gas molecules are bound by Newton’s laws

4. d. The molecules are in constant, random motion

5. e. Carbon dioxide is often regarded as an ideal gas

### Question 10

Which of the following statements regarding gases are true:

1. a. Avogadro’s hypothesis states that at a constant temperature and pressure, equal volumes of ideal gases contain the same number of molecules

2. b. Avogadro’s number is 2.18 × 108

3. c. One mole of any gas at standard temperature and pressure will occupy 22.4 litres

4. d. The critical temperature is defined as the temperature above which a gas cannot be liquefied by any pressure

5. e. The critical pressure is the pressure required to liquefy a vapour at its critical temperature

### Question 11

Linear regression is a term commonly used in statistical analyses of data. Which of the following statements regarding linear regression are true?

1. a. The linear regression coefficient is the gradient of the plotted data

2. b. Analysis yields an intercept that defines the position of the line on the y-axis

3. c. Analysis yields a correlation coefficient that is an indication of the ‘goodness of fit’ of the line to the data

4. d. Linear regression applies a technique of minimizing squared differences

5. e. Both the dependent and the independent variables must be continuous

### Question 12

Randomization of two treatments in a clinical trial means that:

1. a. Results are treated in a random order

2. b. Treatment arms are allocated by reference to a series of random numbers

3. c. Results can be analyzed by Student’s t-test

4. d. Selection bias is reduced

5. e. An independent person allocates the treatment arms

### Question 13

In a study of 600 cancer patients, the distribution of time from diagnosis to death was positively skewed, with a peak at two years and a median survival of three years. The following statements are true:

1. a. The mean survival rate is greater than three years

2. b. The mean survival gives the best guide to the average length of life

3. c. In the first three years after diagnosis 300 patients died

4. d. The mean survival was less than the median survival

5. e. Fewer patients died at the mean time of death than the median

### Question 14

Type I errors in statistics:

1. a. Are false positives

2. b. Are represented by the P value

3. c. Are related to sample size

4. d. Are reduced by double blinding

5. e. Are defined by incorrect rejection of the null hypothesis

### Question 15

Type II errors in statistics:

1. a. Are occurrences of a negative test result when the actual result is positive

2. b. Are true negative errors

3. c. Are defined by incorrect acceptance of the null hypothesis

4. d. Are reduced if the power of a clinical trial is more than 80%

5. e. Are β-errors

### Question 16

If data are normally distributed:

1. a. The mean, median and mode will be the same

2. b. Approximately 96% of the sample data will lie within two standard deviations from the mean

3. c. It demonstrates Gaussian distribution

4. d. It cannot be analyzed by a Student’s t-test

5. e. It cannot be analyzed by non-parametric tests

### Question 17

Regarding non-parametric tests:

1. a. An example is the Mann–Whitney rank sum test

2. b. Imply that the variable cannot be accurately measured

3. c. Can be used on small samples

4. d. Are generally mathematically more complex than parametric tests

5. e. Can be applied to samples that are not normally distributed

### Question 18

The chi-squared test:

1. a. Requires the null hypothesis to be applied

2. b. Measures the overall difference between the observed and expected frequencies

3. c. Is used to prove that one treatment is better than another

4. d. Applies only to continuous variables

5. e. Can have a result of less than zero

### Question 19

Regarding categorical data:

1. a. The data are qualitative

2. b. Interval data is an example

3. c. Ordinal data is an example

4. d. Discrete quantitative data is an example

5. e. Nominal data is the most useful form of categorical data because it can be easily statistically manipulated

### Question 20

Regarding a forest plot:

1. a. Extreme outliers are represented by dots

2. b. Visually demonstrates the range and interquartile range

3. c. Can only be used in normally distributed continuous data

4. d. Usually uses the odds ratio or relative risk on the x-axis

5. e. Meta-analysis results are shown as a diamond

### Question 21

The following are examples of negative exponential processes:

1. a. Xt = X0eY

2. b. Alcohol clearance

3. c. The inflation of the lungs with a Manley ventilator

4. d. Cardiac output measurement using a PA catheter

5. e. Maintenance of anaesthesia using propofol via a target-controlled infusion

### Question 22

1 joule is equal to:

1. a. 1 N.m

2. b. 1 kg.m2.s–2

3. c. 100 000 dyne.m

4. d. 1 Pa.m3

5. e. 1 kg.m–1.s–2

### Question 23

Which of the following statements regarding laminar and turbulent flow are correct?

1. a. In laminar flow, the flow rate is inversely proportional to the fluid viscosity

2. b. In laminar flow, the flow rate is directly proportional to the fourth power of the radius

3. c. Turbulent flow will always be present if the Reynolds number is greater than 1000

4. d. Turbulent flow will always be present if the Reynolds number is greater than 2000

5. e. In turbulent flow, the flow rate is inversely proportional to the fluid density

### Question 24

Regarding flowmeters:

1. a. Oscillatory flowmeters utilize the Coanda effect

2. b. The pneumotachograph is an example of a constant orifice, variable pressure flowmeter

3. c. The rotameter is an example of a variable pressure, variable orifice flowmeter

4. d. A Wright respirometer measures flow

5. e. A Wright respirometer tends to underestimate at low volumes

### Question 25

Which of the following laws are correctly defined?

1. a. Charles’ law: at a constant pressure, the volume of a gas is directly proportional to its absolute temperature

2. b. Henry’s law: at a constant temperature, the amount of gas dissolved in a solvent is proportional to its partial pressure above the solvent

3. c. Dalton’s law: the pressure exerted by a fixed amount of gas in a mixture of gases is equal to the pressure it would exert alone

4. d. Murphy’s law: the osmolality of a solution is equal to the number of osmoles per kilogram of solvent

5. e. Beer’s law: the intensity of transmitted light decreases exponentially as distance travelled through the substance increases

### Question 26

Regarding antistatic footwear worn in theatre:

1. a. The recommended impedance should be between 75 kΩ and 10 MΩ when new

2. b. The impedance should be high enough to prevent dissipation of electrostatic charge

3. c. The impedance should be low enough to protect against electric shock

4. d. They are a mandatory component of the ‘British Standard EN60601’

5. e. Their impedance remains constant even when wet

### Question 27

Regarding Class I electrical equipment:

1. a. It has no symbol

2. b. It requires at least two fuses

3. c. It is double-insulated

4. d. It is the safest for use in theatre

5. e. Any conducting part accessible to the user should be connected to an earth wire

### Question 28

Class II electrical equipment:

1. a. Is usually double-insulated

2. b. Has two squares, one inside the other, as its symbol

3. c. Does not require an earth wire

4. d. Can draw a maximum current of 24 mA

5. e. Can have a single layer of insulation if it is reinforced

### Question 29

Regarding microshock:

1. a. The severity increases as the frequency of the current increases

2. b. The risk is high at mains frequency

3. c. Direct current is more likely to cause microshock than alternating current

4. d. It can only be caused by faulty equipment

5. e. Oesophageal temperature probes are a possible source of microshock

### Question 30

Regarding leakage current standards:

1. a. Type C equipment may be connected directly to the heart

2. b. Type B equipment has the symbol of a square box with a stickman inside

3. c. Type B equipment has a maximum permitted leakage current of 500 µA

4. d. They are set using equipment with a single fault

5. e. Type CF equipment has a maximum permitted leakage current of 100 µA

### Question 31

The Penaz technique:

1. a. Gives intermittent measurement of blood pressure

2. b. Approximates arterial blood pressure by non-invasive means

3. c. Uses photoplethysmography

4. d. Is uncomfortable in awake patients due to compression of the finger

5. e. Uses an infrared beam

### Question 32

Arterial cannulae:

1. a. Should only be flushed with small syringes (less than 5 ml)

2. b. Should be continuously flushed at 10 ml.h–1

3. c. Should have parallel sides

4. d. Are nationally recommended to be inserted using full asepsis including hat, mask, gown and sterile gloves

5. e. Can be inserted in the ulnar artery

### Question 33

Regarding blood pressure measurement:

1. a. A fibreoptic catheter tip transducer can be used

2. b. A Von Recklinghausen oscillotonometer requires a double cuff

3. c. With non-invasive methods the reading may be inaccurate in dysrhythmias

4. d. Radial artery compression can provide a blood pressure waveform

5. e. Ultrasound Doppler can be used to detect changes in the frequency of vibration of the carotid arterial wall to give a blood pressure reading

### Question 34

Regarding fluid manometers:

1. a. Mercury can be used to measure pressures up to atmospheric pressure

2. b. The manometer tube top must not be open

3. c. They can be used to measure gauge pressures

4. d. They can be designed to have a sloped tube

5. e. The effect of surface tension on the liquid inside the manometer can affect the readings

### Question 35

Bourdon gauges:

1. a. Contain liquid that cause a tube to uncoil and move a pointer over a scale on a dial

2. b. Can be used to measure gauge pressures

3. c. Cannot be used for measuring pressures above 100 kPa

4. d. Can be used to measure absolute pressures

5. e. Cannot act as a differential gauge pressure measurement device

### Question 36

The following will increase the damping of an arterial trace:

1. a. Blood clots

2. b. Air bubbles

3. c. A long arterial cannula

4. d. Use of a tourniquet on the measured limb

5. e. An arterial cannula that is too stiff

### Question 37

Moderate damping of an arterial trace can make the following measurements inaccurate:

1. a. Systolic blood pressure

2. b. Diastolic blood pressure

3. c. Mean arterial pressure

4. d. Heart rate

5. e. Stroke volume

### Question 38

Concerning intra-arterial blood pressure monitoring:

1. a. The brachial artery must not be cannulated

2. b. The limb that is cannulated should be kept level with the transducer

3. c. Normal saline should be used in the transducer set in order to minimize the chance of microshock

4. d. The system is designed to keep the resonant frequency above 40 Hz

5. e. Accuracy of strain gauge-type transducers is significantly altered by changes in ambient temperature

### Question 39

Regarding automated non-invasive blood pressure measurement systems:

1. a. They are associated with a 1 in 100 chance of permanent nerve damage distal to the point of application

2. b. They give reliable results in atrial fibrillation

3. c. They detect mean arterial pressure most accurately

4. d. They always require two cuffs

5. e. Oscillations maximally increase in magnitude at systolic pressure

### Question 40

Regarding damping:

1. a. Optimal damping means the system responds rapidly to a change in signal, but allows a small amount of overshoot

2. b. Optimal damping has a coefficient of 0.47

3. c. Underdamping might allow resonance within the system, which has the advantage of more faithful reproduction of the intended waveform

4. d. Critical damping represents the best compromise between response speed and accuracy

5. e. Critical damping has a coefficient of 1.0

### Question 41

Clinical signs of adequate return of neuromuscular function following non-depolarizing neuromuscular blockade include:

1. a. Sustained head lift for at least 3 seconds

2. b. Generation of a vital capacity breath of at least 4 ml.kg–1

3. c. Generation of a vital capacity breath of at least 10 ml.kg–1

4. d. Tidal volume adequate to maintain oxygen saturation above 96%

5. e. Normal respiratory volumes can be generated with only 20% functional diaphragm muscle receptors

### Question 42

There are multiple methods of cardiac output monitoring. Regarding PiCCO as a method, which of the following are true?

1. a. PiCCO stands for ‘power induced contour cardiac output’

2. b. It uses the principle of the Doppler effect

3. c. It requires a central line

4. d. It uses a standard arterial cannula

5. e. It can also give an estimate of intrathoracic blood volume

### Question 43

Concerning train-of-four stimulation:

1. a. The TOF ratio compares the ratio of the strengths of the first and fourth twitches

2. b. Four twitches of 0.5 Hz each are applied over 2 seconds

3. c. On administration of non-depolarizing neuromuscular blocking agent, fade occurs before the disappearance of the twitches

4. d. On recovery, the fourth twitch appears first

5. e. For upper abdominal surgery, at least two twitches must be absent to achieve adequate surgical condition

### Question 44

A clinically useful nerve stimulator for the assessment of neuromuscular block must have the following characteristics:

1. a. It should be able to generate current pulses up to 60 microamps

2. b. It should be powered by a mains transformer to guarantee optimal function

3. c. The supramaximal twitch current should be determined when neuromuscular block is fully developed

4. d. It has leads marked with blue and yellow insulation

5. e. The pulse width should be variable between 0.01 and 0.1 seconds

### Question 45

Which of the following concerning transthoracic impedance (also known as transthoracic electrical bioimpedance) as a method of cardiac output measurement are true?

1. a. It is an invasive method of cardiac output measurement

2. b. It measures the electrical resistance of the thorax

3. c. It uses a low-amplitude, high-frequency alternating current

4. d. It can provide a continuous measurement of cardiac output

5. e. It is unaffected by arrhythmias

### Question 46

The following are characteristics of laminar flow:

1. a. Eddies and turbulence can occur

2. b. Flow rate is greatest at the centre of the flow stream, being twice the flow rate at the side of the tube

3. c. A pressure difference is essential for fluid to flow

4. d. It is impossible to quantify the relationship between pressure and flow without knowing the viscosity and density of the fluid

5. e. Resistance of the tube is a product of the pressure and flow

### Question 47

With regards to turbulent flow in a tube of liquid;

1. a. Flow is inversely proportional to both the square root of the pressure and the square of the tube radius

2. b. Flow is inversely proportional to the square root of the tube length

3. c. Flow is inversely proportional to the square root of the fluid density

4. d. Fluid viscosity becomes increasingly important in determining resistance as the density of the fluid increases

5. e. On transition from laminar to turbulent flow, resistance to flow increases, but less energy is required to generate the same flow

### Question 48

Concerning Wright’s respirometer:

1. a. The device measures gas flow directly by mechanical rotation of vanes

2. b. It is exquisitely accurate for continuous flow

3. c. It is best suited for paediatric practice where flow rates are reduced

4. d. Plotting accuracy against flow rate will yield a U-shaped curve

5. e. It can be used to measure tidal volumes in anaesthesia

### Question 49

The pneumotachograph:

1. a. Is a constant-pressure, constant-orifice device

2. b. Measures volumes, and hence flow can be calculated (volume of gas per unit time)

3. c. The gauze screen causes small eddy currents

4. d. The pressure difference across the gauze screen is proportional to flow

5. e. Some modern pneumotachograph devices employ a variable orifice to maintain laminar flow as fluid flow rates change

### Question 50

Rotameters are commonly seen on anaesthetic machines. Which of the following are true of these devices?

1. a. They are variable-pressure, variable-orifice devices

2. b. They measure gas flow directly

3. c. The glass tube is always tapered

4. d. The pressure across the bobbin changes with flow rate

5. e. Calibration is dependent on both the viscosity and the density of the fluid

### Question 51

Electronic signal analysis is common in a range of anaesthetic monitoring systems. Which of the following are true?

1. a. Electronic noise only occurs in amplifiers

2. b. High-pass filters reject signals below a specified frequency

3. c. Low-pass filters reject signals below a specified frequency

4. d. Notch filters can be used to reject a specific frequency, for example, diathermy interference

5. e. SNR = 10 log10(signal amplitude/noise amplitude)