Physics Chapters 13-30 Exam Review

Chapter 13 – States of Matter
Pressure (P) – the amount of force per unit area.
Pressure=F/a or P=F/a
Pascal’s Principle
“Any change in pressure at a point on a confined fluid is transmitted throughout the fluid”. Any change is transmitted throughout the fluid.
Buoyancy & Archimedes Principle
“When an object is submerged in a fluid, it displaces a certain volume of that fluid. The amount of force pushing upward on the object is equal to the density of the fluid (ρ) times the acceleration due to gravity (g) times the volume of the object (V) This is also equal to the weight of the fluid that the object displaced.”
This is why even heavy steel aircraft carries still float
Bernoulli’s Principle
“As the velocity of a fluid increases, the pressure exerted by that fluid decreases”
This is why airplanes fly

Evaporation is a cooling process
Expansion/Contraction
When you heat up a solid, it expands by a very small amount (that is, small relative to it’s original size). Conversely, when you cool it down, the solid will reduce in size. Different materials expand/contract by different amounts
Water is the only fluid that varies from this. As you cool water from 40C to freezing, water actually expands.

Chapter 14 – Waves
14.1 - Wave Properties
Types of Waves
Transverse – Direction of wave travel is perpendicular to the direction of disturbance that creates the wave.
Longitudinal – Direction of wave travel is parallel to the direction of disturbance that creates the wave

Crests, Troughs, Amplitude, Wavelength (λ), Frequency (f)
Velocity of a wave (v):
14.2 – Wave Behavior
Constructive & Destructive Interference
Nodes – Points of minimum displacement (maximum pressure)
Antinodes – Points of maximum displacement (minimum pressure)

Chapter 15 – Sound
15.1 – Properties of Sound
Sound is a longitudinal wave
Speed of sound in different materials
Fastest in solids, slowest in gases)
Loudness (The Decibel Scale)
Increase of 20 dB Pressure amplitude is 10x larger
Increase of 10dB Sound is “twice as loud”
Increase of 10dB Intensity is 10x the intensity.
Pitch ≈ Frequency (Pitch is the perception of frequency for sound waves)

Doppler Effect
Apparent change in the pitch of a sound caused by the relative motion between the sound source and the observer (e.g. ambulance siren)
15.2 – The Physics of Music
Closed-Pipe Resonators
Resonance lengths, Ln are odd #s of quarter-wavelengths
L1 = (¼) λ, L2 = (¾) λ, etc.
Natural frequencies f1 = v/4L1 f2 = 3·f1 , f3 = 5·f1 , f4 = 7·f1 , etc.
Open-Pipe Resonators
Resonance Lengths, Ln are even #s of quarter-wavelengths
L1 = (2/4)λ , L2 = (4/4)λ , etc.
Natural Frequencies f1 = v/2L f2 = 2·f1 , f3 = 3·f1 , f4 = 4·f1 , etc.
Beat Frequency, fbeat created when playing two notes together, fA and fB, that have almost the same frequency

Chapter 16 – Light
16.1 - Light fundamentals
Illuminance – rate at which light falls on a surface Doubling d will make ε (¼) as much
16.2 – Light and Matter
Additive Primary Colors – Red, Green, Blue
Subtractive Primary Pigments – Yellow, Cyan, Magenta
Polarization of light
Only when two polarizing filters are at right angles to each other, no light comes through

Chapter 17 – Reflection and Mirrors
Law of Reflection
Angle of Incidence = Angle of Reflection

Mirrors (Reference Table 17-1)
Plane Mirrors (i.e. flat mirrors)
Create a right-side-up, undistorted, virtual image with a magnification of one
The Lens/Mirror Equations di is positive for real images in mirrors di is negative for virtual images in mirrors
Images
Draw Ray diagram: Across, through focal. through focal, across

Chapter 18 – Refraction and Lenses
18.1 Refraction – The bending of light caused when light moves from one medium to another.
Index of Refraction (η)
η = c/v
Snell’s Law of Refraction ni = index of refraction of incident (initial) material nr = index of refraction of refracting (final) material
θi = angle of incidence (from the normal)
θr = angle of refraction (from the normal)
Going from low n to higher n (air to glass), light bends towards the normal
Going from high n to lower n (glass to air), light bends away from normal
Refraction does not change the frequency of the light
18.2 – Lenses (Table 18-2) di is negative for virtual images di is positive for real images
Concave Lenses (“diverging lens”) f is negative for concave lenses
Convex Lenses (“converging lens”) f is positive for convex lenses
Magnification, m
If (m < 0) image is inverted, otherwise it is upright
If |m| > 1 image is larger than object
If |m| Ns

Chapter 26 – Electromagnetism
The ratio of charge to mass of an electron was measured by J. J. Thomson using balanced electric and magnetic fields in a cathode-ray tube. q / m = v /( β r )
A mass spectrometer used both electric and magnetic fields to measure the masses of ionized atoms and molecules. q / m = 2 V / ( β2 r2 )
Electromagnetic waves are generated by varying electric fields and magnetic fields that are perpendicular to each other and travel through space at the speed of lights. v = λ f
All electromagnetic waves travel at the same speed. Speed depends only on the medium.

Chapter 27 – Quantum Theory
Planck’s constant, h = (6.63x10-34) J/Hz - ratio of photon energy to photon frequency
Energy of a photon, E = hf Speed of a photon = c = speed of light = (3×108)m/s
1 Electron-Volt (eV) = (1.6x10-19) Joules
E = hc / λ = 1240 eV nm/ λ
Photoelectric Effect
Radiation will eject electrons from a given material if the frequency of the radiation is above the threshold frequency, f0 for that material.
Momentum of a photon deBroglie wavelength
Heisenberg Uncertainty Principle
It is impossible to accurately measure both the momentum and position of a particle. Whenever you measure one, you disrupt the other.
Chapter 28 - The Atom
Rutherford Model – based on gold foil experiment, positive charge is concentrated in the nucleus
The nucleus
The nucleus is located at the center of the atom
It makes up 99.999% of the mass of the atom
It contains protons and neutrons, which have approximately equal masses of 1 atomic mass unit (1u)
Laser- Intense coherent light

Chapter 30 – Nuclear Physics
30.1 – Radioactivity
Isotopes – different number of neutrons but same number of protons (same element) Z = # protons (i.e. atomic #) A = #(protons + neutrons)
Example: “Uranium-238” 92 Protons
+146 Neutrons 238 Total particles in the nucleus
Alpha Decay
Beta Decay
Gamma Decay
Highly penetrating, high-energy photons
30.2 – Half-Life (H) or Remaining = Original (1/2)t
After each half-life, half of the sample is gone
@ 2·H 1/4 , @3·H 1/8 , @4·H 1/16