Grade 11 Physical Sciences Summaries. This summaries are composed using the Via Afrika textbooks' term 2 work with examples and supplementary notes.
Chapter 3: Waves, Sound and Light
Unit 1: Geometrical Optics
Unit 2: 2D & 3D Wavesfronts
Chapter 4: Matter and Materials
Unit 1: Id...
Reflection:
• Incident ray = ray going towards mirror.
• Reflected ray = ray coming from mirror.
• Normal = imaginary line perpendicular to surface
from which the light is reflected.
• Angle i = angle of incidence.
• Angle r = angle of reflection.
• Laws of reflection:
- Angle of incidence = angle of reflection.
- Incident ray, normal and reflected ray are all
in the same plane.
U1:
Sample
Geometrical
Refraction: Snell’s Law:
Optics (A)
• Refraction = the change in the direction of
light when it enters a new medium. • If ray of light enters glass with angle
• Light slows down when it enters glass and of incidence θ1.
then speeds up when it enters air again. • Angle of refraction (θ2) is smaller than
Summaries after sample
•
•
Optical Density:
• The more the light slows down, the
Refractive Index:
• Speed of light is constant when
passed through given medium.
θ1.
• θ2 will increase if θ1 increases, but
they aren’t directly proportional.
𝑠𝑖𝑛𝜃
• n = 𝑠𝑖𝑛𝜃1 .
2
• n1 sinθ1 = n2 sinθ2.
• Refraction index = ratio of velocity of
greater the amount of refraction.
light in space (c) to velocity of light in
• Optical density = degree to which the
medium (v).
medium slows the light down. 𝑐
• n=𝑣.
• Beam of light composed of parallel
transverse waves enters glass at an • When light enters medium of greater
angle of incidence of 0°: optical density at an angle:
- Doesn't deviate. - Frequency stays constant.
- Wavelength decreases. - Period stays constant.
• When a beam strikes glass at an angle: - Speed decreases.
- Beam refracts towards normal - one - Wavelength decreases.
side of beam slows down first. - Bends towards normal.
, Motion of Particles:
Gay-Lussac’s Law:
• Gay-Lussac's law = The pressure of a fixed
mass of gas with a constant volume is directly
proportional to the temperature.
• Temp. is increased – particles have more
energy – exert greater pressure on container.
𝑝 𝑝
• 1= 2.
𝑇1 𝑇2
𝑝1 𝑉1 𝑝2 𝑉2
• Combination of the laws: 𝑇1
= 𝑇2
. Behaviour of Non-
• Avogadro’s principle = equal volumes of Ideal Gases:
different gases at the same temp. and
Sample pressure will contain the same no. of particles. • Particles of real gas occupy space – low
temp. causes volume of real gas to be
U1: Ideal Gases more than ideal gas.
• Real gases can’t be compressed to
& Thermal expected volume when the pressure is
• Ideal Gas Equation: Properties (B) high – V is greater, so pV is also greater.
Summaries after sample
•
• Combines Boyle’s law and Charles’s
relationship.
• V∝𝑝.
𝑇
SI Units & the Ideal
• High pressure causes particles to become
closer - real volume of particles come into
effect.
• Ideal gas law can’t be used under very low
temps. or very high pressure.
• pV = nRT.
Gas Equations:
• Pressure = Pa.
- 1kPa = 1000Pa.
• Volume = m3 – usually given in dm3 or ℓ.
- 1ℓ = 1dm3 = 0,001m3.
• Temp. = K – usually given in °C.
- K = °C + 273.
, Relationship Between
Volume Relationships Volume, Temp. & Pressure:
in Gaseous Reactions: • More accurate value for volume of
gas used can be calculated using the
Ammonium Nitrate in Mining: general gas equation (pV = nRT) if
Functioning of Airbags:
actual values of pressure and temp. • Object hits airbag position with enough force
• 2NH4NO3(s) (in presence of heat) -> 2N2(g) +
are known. – sensor causes electrical spark.
4H2O(g) + O2(g).
• E.g. 10g of NH4NO3 used. 2 moles of solid NH4NO3 • Spark ignites small sodium azide pellet.
produces (2 + 4 + 1) moles gas. How to calculate • 2NaN3(s) -> 2Na(s) + 3N2(g).
volume of gas produced: • Nitrogen gas rapidly fills airbag – causes it to
𝑚𝑎𝑠𝑠
- nammonium nitrate = 𝑀 = 10g ÷ (14 + 4 x 1 + 14 + 3 burst out of the dashboard or steering wheel.
Sample
-
-
-
10
x 16) = 80= 0,125 mol.
2 mol NH4NO3 -> 7 mol gas.
0,125
0,125 mol NH4NO3 -> 2 x 7 = 0,438 mol gas.
Volume gas produced at STP = 22,4 x 0,438 =
U1: Quantitative
Aspects of Chemical
Change (C)
• Sodium azide is harmful – KNO3 also placed
into airbag to react with sodium:
10Na(s) + 2KNO3(s) -> 2K2O(s) + N2(g).
• Reaction is exothermic – volume of nitrogen
produced will be larger than what is
Summaries after sample
9,81dm3. calculated, at resulting higher temp.
• E.g. if airbag must inflate to a volume of
27dm3:
27
- 22,4 mol N2 gas required to get a volume
Petrol in a Car Engine: of 27dm3.
27
• 2C8H18(g) + 25O2(g) -> 16CO2(g) + 18H2O(g). - = 1,21 moles N2.
22,4
• Octane and oxygen are sucked into the cylinder – - 2mol NaN3 produces 3 mol N2:
1,21
mixture is compressed by pistons pushing into *1,21 mol N2 produced from 3 x 2mol
cylinder – reduces volume. NaN3 = 0,81mol NaN3.
• Spark produced by spark plug – causes reaction *Molar mass (M) of sodium azide is [23 +
between oxygen and fuel. 3 x 14] = 65g.mol-1.
• Large production of CO2 and water vapour causes *Mass NaN3 required = n x M = 0,81 x 65
explosion – gas explosion pushes piston down = 52,7g NaN3.
again – process restarts. *Compressed into pellet.
-
, Reflection:
• Incident ray = ray going towards mirror.
• Reflected ray = ray coming from mirror.
• Normal = imaginary line perpendicular to surface
from which the light is reflected.
• Angle i = angle of incidence.
• Angle r = angle of reflection.
• Laws of reflection:
- Angle of incidence = angle of reflection.
- Incident ray, normal and reflected ray are all
in the same plane.
U1:
Geometrical
Refraction: Snell’s Law:
Optics (A)
• Refraction = the change in the direction of
light when it enters a new medium. • If ray of light enters glass with angle
• Light slows down when it enters glass and of incidence θ1.
then speeds up when it enters air again. • Angle of refraction (θ2) is smaller than
• θ1.
•
Refractive Index: • θ2 will increase if θ1 increases, but
they aren’t directly proportional.
Optical Density: • Speed of light is constant when 𝑠𝑖𝑛𝜃
• n = 𝑠𝑖𝑛𝜃1 .
passed through given medium. 2
• The more the light slows down, the • n1 sinθ1 = n2 sinθ2.
• Refraction index = ratio of velocity of
greater the amount of refraction.
light in space (c) to velocity of light in
• Optical density = degree to which the
medium (v).
medium slows the light down. 𝑐
• n=𝑣.
• Beam of light composed of parallel
transverse waves enters glass at an • When light enters medium of greater
angle of incidence of 0°: optical density at an angle:
- Doesn't deviate. - Frequency stays constant.
- Wavelength decreases. - Period stays constant.
• When a beam strikes glass at an angle: - Speed decreases.
- Beam refracts towards normal - one - Wavelength decreases.
side of beam slows down first. - Bends towards normal.
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller SummariesSA. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.48. You're not tied to anything after your purchase.
