measurement

1. Physics and PhysicalPhysics and Physical
MeasurementMeasurement
Topic 1.1 The Realm of PhysicsTopic 1.1 The Realm of Physics
Range of magnitudes of quantities inRange of magnitudes of quantities in
our universeour universe

2. List as many physical quantitiesList as many physical quantities
as you can…in two minutesas you can…in two minutes
LengthLength
MassMass
TimeTime
TemperatureTemperature
EnergyEnergy
VelocityVelocity
AccelerationAcceleration
ForceForce
ChargeCharge
CurrentCurrent
AngleAngle
FrequencyFrequency
WavelengthWavelength
ResistanceResistance
Potential DifferencePotential Difference
Specific heat capacitySpecific heat capacity

3. Range of MagnitudesRange of Magnitudes
You will need to be able to state (express)You will need to be able to state (express)
quantities to the nearest order ofquantities to the nearest order of
magnitudemagnitude
That is to say to the nearest 10That is to say to the nearest 10xx

4. Powers of TenPowers of Ten
http://micro.magnet.fsu.edu/primer/java/scihttp://micro.magnet.fsu.edu/primer/java/sci

5. Amend your listAmend your list
For each of the quantities we listed you nowFor each of the quantities we listed you now
estimate their size, it can be a rangeestimate their size, it can be a range
Eg anglesEg angles
101000
to 10to 1022

6. Range of magnitudes ofRange of magnitudes of
quantities in our universe (1)quantities in our universe (1)
Sizes (Distances)Sizes (Distances)
• From 10From 10-15-15
mm
(subnuclear particles)(subnuclear particles)
• To 10To 10+26+26
mm
(extent of the visible universe)(extent of the visible universe)

7. Range of magnitudes ofRange of magnitudes of
quantities in our universe (2)quantities in our universe (2)
MassesMasses
• From 10From 10-30-30
kgkg
(electron mass)(electron mass)
• To 10To 10+50+50
kgkg
(mass of the universe)(mass of the universe)

8. Range of magnitudes ofRange of magnitudes of
quantities in our universe (3)quantities in our universe (3)
TimesTimes
• From 10From 10-23-23
ss
(passage of light across a nucleus)(passage of light across a nucleus)
• To 10To 10+18+18
ss
(age of the universe)(age of the universe)

9. RatiosRatios
You will also be required to state (express) ratiosYou will also be required to state (express) ratios
of quantities as differences of order of magnitudeof quantities as differences of order of magnitude
Example:Example:
The hydrogen atom has a diameter of 10The hydrogen atom has a diameter of 10-10-10
mm
Whereas the nucleus is 10Whereas the nucleus is 10-15-15
mm
The difference is 10The difference is 1055
• A difference of 5 orders of magnitudeA difference of 5 orders of magnitude

10. Now try these ratiosNow try these ratios
Mass of electron to your massMass of electron to your mass
Radius of atom to your heightRadius of atom to your height
Mass of electron to mass of uranium atomMass of electron to mass of uranium atom
Radius of Earth to size of universeRadius of Earth to size of universe

11. SolutionsSolutions
Mass of electron to your massMass of electron to your mass
1010-30-30
/ 10/ 1022
= 10= 10-32-32
so 32 orders of mag.so 32 orders of mag.
Radius of atom to your heightRadius of atom to your height
1010-10-10
/ 10/ 1000
= 10= 10-10-10
so 10 orders of mag.so 10 orders of mag.
Mass of electron to mass of uranium atomMass of electron to mass of uranium atom
1010-30-30
/ 10/ 10-25-25
= 10= 10-5-5
so 5 orders of mag.so 5 orders of mag.
Radius of Earth to size of universeRadius of Earth to size of universe
101077
/ 10/ 102626
= 10= 10-19-19
so 19 orders of mag.so 19 orders of mag.