Quantity, Symbol, Unit, Unit Symbol

Comments from the Workshop


Clicking on the link above will take you to the You Must Justify Questions that we didn’t have time for! Please look over this.


CfE Higher Revision Cards A4

Quantity, Symbol, Unit, Unit Symbol

I’ve put together, with Mrs Mac’s help, a document with quantity, symbol, unit and unit symbol so that you know the meaning of the terms in the Relationships Sheet. It is in EXCEL so that you can sort it by course, quantity or symbol.

Quantity, Symbol, Units the excel sheet

Quantity, Symbol, Units a pdf sheet sorted by course and then alphabetical by quantity.

This is the same information in readily available Tablepress form. If you click on the Higher tab at the top it should sort by terms that you need in alphabetical order, or search for a term. Let me know if I’ve missed any.

Quantity, Symbol, Unit, Unit Symbol Table for N5-AH

NHAPhysical Quantity symUnitUnit Abb.
5absorbed dose D gray Gy
5absorbed dose rate H (dot)gray per second gray per hour gray per year Gys-1 Gyh -1 Gyy-1
567acceleration a metre per second per second m s-2
567acceleration due to gravity g metre per second per second m s -2
5activity A becquerel Bq
567amplitude A metre m
567angle θ degree °
567area A square metre m 2
567average speedv (bar)metre per second m s-1
567average velocity v (bar)metre per second m s -1
567change of speed ∆v metre per second m s -1
567change of velocity ∆v metre per second m s-1
5count rate - counts per second (counts per minute) -
567current I ampere A
567displacement s metre m
567distance dmetre, light year m , ly
567distance, depth, height d or h metre m
5effective dose H sievert Sv
567electric charge Q coulomb C
567electric charge Q or q coulomb C
567electric current I ampere A
567energy E joule J
5equivalent dose H sievert Sv
5equivalent dose rate H (dot)sievert per second sievert per hour sievert per year Svs-1 Svh-1 Svy -1
567final velocity v metre per second m s-1
567force F newton N
567force, tension, upthrust, thrustF newton N
567frequency f hertz Hz
567gravitational field strength g newton per kilogram N kg-1
567gravitational potential energy Epjoule J
5half-life t1/2 second (minute, hour, day, year) s
56heat energy Eh joule J
567height, depth h metre m
567initial speed u metre per second m/s
567initial velocity u metre per second m s-1
567kinetic energy Ek joule J
567length l metre m
567mass m kilogram kg
5number of nuclei decayingN - -
567period T second s
567potential difference V volt V
567potential energy Ep joule J
567power P watt W
567pressure P or p pascal Pa
5radiation weighting factor wR- -
567radius r metre m
567resistance R ohm Ω
567specific heat capacity c joule per kilogram per degree Celsius Jkg-1°C -1
56specific latent heat l joule per kilogram Jkg-1
567speed of light in a vacuum c metre per second m s-1
567speed, final speed v metre per second ms -1
567speed, velocity, final velocity v metre per second m s-1
567supply voltage Vsvolt V
567temperature T degree Celsius °C
567temperature T kelvin K
567time t second s
567total resistance Rohm Ω
567voltage V volt V
567voltage, potential difference V volt V
567volume V cubic metre m3
567weight W newton N
567work done W or E Wjoule J
7angle θ radian rad
7angular acceleration aradian per second per second rad s-2
7angular displacement θ radian rad
7angular frequency ω radian per second rad s-1
7angular momentum L kilogram metre squared per second kg m2s -1
7angular velocity,
final angular velocity
ω radian per second rad s-1
7apparent brightnessbWatts per square metreWm-2
7back emfevolt V
67capacitance C farad F
7capacitive reactance Xcohm W
6critical angle θc degree °
density ρ kilogram per cubic metre kg m-3
7displacement s or x or y metre m
efficiency η - -
67electric field strength E newton per coulomb
volts per metre
N C-1
7electrical potential V volt V
67electromotive force (e.m.f) E or ε volt V
6energy level E1 , E2 , etcjoule J
feedback resistance Rfohm Ω
focal length of a lens f metre m
6frequency of source fs hertz Hz
67fringe separation ∆x metre m
67grating to screen distance D metre m
7gravitational potential U or V joule per kilogram J kg-1
half-value thickness T1/2 metre m
67impulse (∆p) newton second
kilogram metre per second
7induced e.m.f. E or ε volt V
7inductor reactanceXLohm W
7initial angular velocity ω oradian per second rad s-1
input energy E ijoule J
input power Piwatt W
input voltage V1 or V2 volt V
input voltage V ivolt V
6internal resistance r ohm Ω
67irradiance I watt per square metre W m-1
7magnetic induction B tesla T
7moment of inertia I kilogram metre squared kg m2
67momentum p kilogram metre per second kg m s-1
6number of photons per second per cross sectional area N - -
number of turns on primary coil np- -
number of turns on secondary coil ns- -
6observed wavelengthλobservedmetrem
output energy Eo joule J
output power Powatt W
output voltage Vo volt V
6peak current Ipeak ampere A
6peak voltage V peak volt V
7phase angle Φ radian rad
67Planck’s constant h joule second Js
7polarising angle
(Brewster’s angle)
ipdegree ̊
power (of a lens) P dioptre D
power gain Pgain - -
7Power per unit areaWatts per square metreWm-2
primary current Ip ampere A
primary voltage Vpvolt V
7radial acceleration ar metre per second per second m s-2
67refractive index n - -
6relativistic lengthl'metrem
6relativistic timet'seconds
rest mass mo kilogram kg
6rest wavelengthλrestmetrem
6root mean square current I rmsampere A
6root mean square voltage Vrmsvolt V
7rotational kinetic energy Erotjoule J
7schwarzchild radiusrSchwarzchildmetrem
secondary current Is ampere A
secondary voltage Vsvolt V
7self-inductance L henry H
67slit separation d metre m
7tangential acceleration atmetre per second per second m s-2
6threshold frequency fohertz Hz
7time constanttseconds
7torque Τ newton metre Nm
7uncertainty in Energy∆E jouleJ
7uncertainty in momentum∆px kilogram metre per second kgms-1
7uncertainty in position∆x metre m
7uncertainty in time∆t seconds
6velocity of observer vometre per second m s-1
6velocity of source vsmetre per second m s-1
voltage gain - - -
voltage gain Ao or V gain - -
6work functionWjouleJ



It is really important that you get to grips with the uncertainty section. You will need this information for your Assignment and it could well form a question on the exam paper.

The key is remembering that ANY measurement is liable to uncertainty. Get that and you’re half way there!

Here is a summary of Key Knowledge for this section new for 2021


Random and systematic uncertainty

Uncertainties and data analysis

  • All measurements of physical quantities are liable to uncertainty, which should be expressed in absolute or percentage form. Random uncertainties occur when an experiment is repeated and slight variations occur. Scale reading uncertainty is a measure of how well an instrument scale can be read. Random uncertainties can be reduced by taking repeated measurements. Systematic uncertainties occur when readings taken are either all too small or all too large.
  • They can arise due to measurement techniques or experimental design.
  • The mean of a set of readings is the best estimate of a ‘true’ value of the quantity being measured. When systematic uncertainties are present, the mean value of measurements will be offset. When mean values are used, the approximate random uncertainty should be calculated. When an experiment is being undertaken and more than one physical quantity is measured, the quantity with the largest percentage uncertainty should be identified and this may often be used as a good estimate of the percentage uncertainty in the final numerical result of an experiment. The numerical result of an experiment should be expressed in the form final value ±uncertainty.


Whenever you do an experiment there will be uncertainties.

There are three types of uncertainty and effects to look out for at Higher.

Systematic Effects

Here the problem lies with the design of the experiment or apparatus. It includes zero errors. Sometimes they show up when you plot a graph but they are not easy to recognise, as they are not deliberate. Systematic effects include slow running clocks, zero errors, warped metre sticks etc. The best way to ensure that these are spotted is to acknowledge their existence and go looking for them. Where accuracy is of the utmost importance, the apparatus would be calibrated against a known standard. Note that a systematic effect might also be present if the experimenter is making the same mistake each time in taking a reading.

Random Uncertainties

These uncertainties cannot be eliminated. They cannot be pinpointed. examples include fluctuating temperatures, pressure and friction. Their effect can be reduced by taking several readings and finding a mean.

Reading Uncertainties

These occur because we cannot be absolutely certain about our readings when taking measurements from scales. Use scales with mirrors where possible, good scales and repeat all measurements.

Repeat all experiments to reduce the reading and random uncertainties. Systematic effects are not improved by taking lots of results.

Which experiment has the best design?

Quantifying Uncertainties

 1.Find the mean

This is the best estimate of the “true” value but not necessary the “true” value.

          2. Find the approximate random uncertainty in the mean (absolute uncertainty)

This can be written as  and it is sometimes referred to as average deviation or absolute uncertainty.

3. Find the percentage uncertainty.


Scale Reading Uncertainty

This value indicates how well an instrument scale can be read.

An estimate of reading uncertainty for an analogue scale is generally taken as:

± half the least division of the scale.

Note: for widely spaced scales, this can be a little pessimistic and a reasonable estimate should be made.

For a digital scale it is taken as

± 1 in the least significant digit displayed.

Or uncertainty in reading ÷reading × 100%

Overall final Uncertainty

When comparing uncertainties, it is important to take the percentage in each.

In an experiment, where more than one physical quantity has been measured, spot the quantity with the largest percentage uncertainty. This percentage uncertainty is often a good estimate of the percentage uncertainty in the final numerical result of the experiment.

eg if one measurement has an uncertainty of 3% and another has an uncertainty of 5%, then the overall percentage uncertainty in this experiment should be taken as 5%



Introduction Tasks

Friday 9th June
learning outcomes
  1. To review the work completed so far
  2. To practice uncerts and practical experiments
  3. To practice risk assessments


    1. Starting on approximately p14 of the introduction notes complete tutorial 1 & 2
    2. Make notes on uncerts and quantifying them from chapter 4
    3. Risk assessment -Go through the powerpoint on the network (higher physics-> intro-> on risk assessment)
    4. In your classwork jotter answer the questions as you go through the power point
    5. Complete the practical below and write it up, including hazards, risks and controls.
    Checking Your Uncertainties.

    Aim:      To find the average speed of a trolley moving down a slope, estimating the uncertainty in the final value.

    Apparatus: 1 ramp, 1 metre stick, 1 trolley, 1 stop clock.


    1. Set up a slope and mark two points 85 cm apart.
    2. Note the scale reading uncertainty.
    3. Calculate the percentage uncertainty in the distance.
    4. Ensuring the trolley starts from the same point each time, measure how long it takes the trolley to pass between the two points.
    5. Repeat 5 times, calculate the mean time and estimate the random uncertainty.
    6. Note the scale reading uncertainty in the time.
    7. Calculate the percentage uncertainty in the time.
    8. Calculate the average speed and associated uncertainty.
    9. Express your result in the form:

    (speed ± absolute uncertainty) m s-1

    Write up your experiment and include your risk assessment

    1. Continue with the tutorials on Uncerts.