Cambridge IGCSE Physics(0625)
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Contents
• Block 1_ General Physics (Chapter_ 1-8)
• Block 2_ Thermal Physics (Chapter_ 9-11)
• Block 3_ Physics of Waves(Chapter_ 12-15)
• Block 4_ Electricity and MagneHsm(Chapter_ 16-21)
• Block 5_ Atomic Physics( 22-23)
• Block 6_ Space Physics( 24-25)
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Introduction to Physics
The word Physics comes from Ancient
Greek: Physike, meaning the knowledge
of the world.
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What is Physics?
Physics is the study of our natural world
_from the very large(e .g. the solar system to the very small item(e.g. the atom)
How many major topics can be divided/categorized
for the Study of Physics?
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What is Physics?
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What is Physics?
MATTER
Physics
ENERGY
Is the study of
General Physics Thermal Physics Light, Waves
& Sound
Electricity&
MagneHsm
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How we received the knowledge we have
gained in the field of Physics?
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What are Prerequisites?
Ø Physical Quantities
Ø Measurements Techniques
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Ø Physical QuanMMes
When travelling within a country( e,g,
Singapore), you may have noHced that
the most overhead bridges have a sign
with 4.5 m printed of them.
In Physics, height is a physical quantity_ ’4.5’ is
the numerical magnitude and ‘m’ is the unit
(Figure 1)
Figure. This sign found on an overheaded bridge warns drivers of vehicles
above the height of 4.5 m not to pass underneath it.
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What is a physical quanMty?
A physical quanMty is a feature of something which can be measured.
Example, length, mass, time of fall, etc.
vEvery physical quantity has a numerical value and a unit.
If some one says they have a waist measurement of 50, they could be very
slim or fat depending on Whether the measurement is in centimeters or
inches!
Take care!-It is vital to give the unit of measurement
whenever a quanHty is measured or wri^en down.
A Physical quanHty is a quanHty that can be measured.
It consist of a numerical magnitude and a unit.
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Example of some Physical QuanHHes:
QuanHHes of of some physical observablesThe length of a paper, the area of a cylinder tube,
the volume of water and distance between the earth and Sun, mass of a nail, density of
Water, temperature of materials, etc.
Note:
Ø A physical quanHty is a physical property of material or system that can be quanHfied
by measurement.
Or the quanHty of a material that can be measured
Ø A physical quanHty can be expressed as a value,
which is the algebraic mulHplicaHon of a numerical value and a unit.
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Different Physical Observables/ QuanHHes
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Question
• What do we need to do before measurements?
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Defining Units and Basic QuanMMes
v Before a measurement can be made, a standard or
unit must be chosen.
v The size of the quantity to be measured is then
found with an instrument having a scale marked in
the unit.
v Three basic quantities we measure in physics are
length, mass and time. Units for other quantities
are based on them.
Under What System?
v The SI (Système InternaHonal d’Unités) system is a set of
metric units now used in many countries.
It is a decimal system in which units are divided or mulHplied
by 10 to give smaller or larger units.
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Why do we need SI units?
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Note:
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Base quanHHes and Derived quanHHes
What does basic quanHty mean and derived quanHty stand for?
(i)Base QuanHHes_ the fundamental and basic quanHHes
that are not defined by other quanHHes
(ii) Derived QuanHHes -_ derive form the combining of two basic quanHHes
Speed= distance/time(s)=
m per second
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How do we make measurements?
Obviously, there is a short distance to be measured and long
distance as well.
Different Size( amount/value)
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Measuring instruments on the flight deck of a passenger jet
provide the crew with informaHon about the performance of
the aircram (see Figure 1.1.1).
How do we describe numbers and units when it is bigger or smaller ?
We can make a unit bigger or smaller by putting an extra symbol, called a prefix, in front.
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How do we describe numbers when it is bigger or smaller ?
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How do we describe numbers and units ?
Way describing the numbers: Decimal, fracHon and ScienHfic notaHons
Ways to describe numbers: expressing power form and adding the power form
as prefixes shorthand way in front of unit?
Scientific Notation!!!
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Three Base Quantities
• Length
• Mass
• Time
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