# Physics 2nd Semester Exam

## Terms

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What is a rythmic disturbance that carries energy through matter or space?
Wave
What is a single disturbance traveling through a medium?
Wave pulse
What are the two main types of waves?
Electromagnetic and mechanical
What type of waves do not need a medium to travel through?
Electromagnetic
What type of waves require a source of energy and an elastic medium?
Mechanical
2 main kinds of mechanical waves
Transverse and longitudinal
type of mechanical waves causes particles to vibrate perpendicular to the direction of the wave
Transverse
type of mechanical waves causes particles to vibrate parallel to the direction of the wave
Longitudinal
position (displacement) and motion (velocity) of a point on a wave
Phase
Points on a wave are 180 degrees out of phase if...
They have equal and opposite displacements and velocities
linear distance between any point on the wave and the next closest point that's in phase with it
Wavelength
number of wavelengths/pulses that pass a given point each second
Frequency
time required for one wavelength/pulse to pass a given point
Period
SI unit of frequency
Hertz
linear distance traveled by the wave per unit of time
speed
EQUATION: V=
(lambda) f
-------- OR -------
T (lambda)
max displacement of vibration particles from their equilibrium position
Amplitude
loss of energy (amplitude) due to friction
damping
Speed of Waves
1)doesn't depend on..
2)doesn't depend on..
3)depends on..
1)energy being transmitted
2)amplitude of wave
3)nature of wave and the medium
waves propogate in a straight line perpendicular to the wave front
rectilinear propogation
EQUATION: Law of reflection
angle i = angle r
bending of a wave around edge of a barrier
diffraction
points of zero displacement
nodes
points of max displacement
loops
sound waves are these types of mechanical waves
longitudinal
speed of sound in air at room temp.
343 m/s
amplitude of sound as measured on a log scale
sound level
sound level is measured in..
decibels
loudness of sound depends on 2 things..
amplitude and frequency
___ dB increase is perceived as a doubling of the loudness
10
most people can't hear below ___ Hz or above ___ Hz
20-16,000
people are most sensitive to sounds between ___ & ___ Hz
1,000-5,000
frequency of a sound wave
pitch
change in pitch due to relative motion between sound source and the ear
dopplar shift
created by constructive interference; high pressure wall that an object has to pass through to go faster than speed of sound
sound barrier
spy plane; flies 5 mi higher than other aircraft; fastest aircraft; almost invisible to radar
blackbird
fighter/bomber plane; often invisible to radar
nighthawk/stealth fighter
vibrating sound source is placed in contact with a larger object and forces it to vibrate
forced vibrations
a force is applied to an object everytime it undergoes a complete vibration
resonance
easiest frequency to produce in an object
natural frequency
a closed-pipe or open-pipe resonator resonates at ____ intervals
1/2 lambda
EQUATION:
L(b) - L(a) =
1/2 lambda
sound produced by an object vibrating only at its natural frequency
pure tone
tones which come from vibrations having a frequency greater than the fundamental frequency
over tones
depends on the number of overtones produced; richness
quality/timbre
refers to the number of overtones present plus their intensity
harmonic content
general string EQUATION:
k=
f x l x d x '/D
---------------
'/F
interference effect from the superposition of 2 waves of slightly different frequency
beat
# of beats per sec =
difference between frequency of component waves
human ear can recognize up to ____ beats per sec
10
3 properties of light known during the 17th century
1)regular reflection
2)refraction
3)rectilinear propogation
this theory said light consists of very small particles moving at a very fast speed; advocated by Newton
Particle Theory
this theory said light was a wave; advocated by Huygens
Wave Theory
Huygens
Newton
this man discovered light travels slower in water than air
Foucault
developed the electromagnetic theory
James Clerk Maxwell
confirmed the electromagnetic theory experiementally
Hertz
radiation just before red; gives sensation of warmth; causes atoms and molecules to move
radiation just beyond violet; 3 different types
discovered x-rays
Roentgen
Becquerel
discovered the electron
Thomson
3 radioactive elements.. 2 were discovered by the Curies
alpha, beta, gamma
date of the birth of modern physics
1900
this hypothesis said vibrating particles in the hot objects studied only emit packets of energy
Planck's Quantum Hypothesis
packets of energy
quanta/photons
EQUATION: Planck's Quantum Hypothesis
E=
h x f
the emmission of electrons by a substance when illuminated by electromagnetic radiation
photoelectric effect
man who published the first quantitative studies of the photoelectric effect
Lenard
says light is made up of quanta/photons; explained the photoelectric effect
Einstein's Quantum Theory of Light
atomic spectra were first discovered by these 2 men
Kirchoff and Bunsen
order of the models of the atom
Dalton's indestructable; Thomson's plum pudding; Rutherford's nuclear; Bohr's planetary
discovered electric arc lamp
Davy
invented the first practical bulb
Edison
most efficient light
Fluorescent
science of how light interacts with life
photobiology
proposed that matter has wave properties
de Broglie
EQUATION:
wavelength of matter =
h
---------
m x v
these two men confirmed de Broglie's prediction of the wavelength of matter
Davison & Germer
light with the same frequency
monochromatic
LASER =
Light Amplification by Stimulated Emission Radiation
first person to make a careful study of color
Newton
band of colors
solar spectrum
light consisting of many colors
polychromatic
2 properties of glass
transparent & dispersive
this spectrum is produced by incandescent solids, liquids, or gases under high pressure
continuous
this spectrum is produced by exciting a low density gas with heat or electricity
bright-line
this spectrum is produced by passing white light through a cool gas
dark-line spectrum
man who discovered the dark lines in the solar spectrum
Fraunhofer
if a star has a high frequency shift, it's moving
toward us
if a star has a low frequency shift, it's moving
away from us
complementary colors..
1)Red
2)Green
3)Blue
1)Cyan
2)Magenta
3)Yellow
3 primary colors of light
red, green, blue
3 primary pigments
magenta, yellow, cyan
you can see a rainbow when..
1)the sun is behind you
2)angle formed is 40-42
light that only vibrates in one plane
polarized light
emission of light during the absorption of radiation
fluorescence
emission of light after the light sorce has been removed
phosphorescence
EQUATION: law of refration (snell's law)
n =
sin i V(air)
n = ----- = -----
sin r V(material)
branch of electronics that deals with static electricity
electrostatics
matter through which an electron can easily pass
conductor
matter through which electons can't easily pass through
insulator
EQUATION:
F =
Q1 x Q2
K x -------
d^2
described by lines of flux
magnetic field
described by lines of force
electric field
EQUATION: Electric Field Intensity
E=
F/q
rate of flow of charge through a conductor
electric current
SI unit of electric current
ampere (A)
opposition electrons encounter as they pass through conductor
electric resistance
SI unit of resistance
ohm
conducting loop of wire through which a current can transfer electric energy from a suitable source to a useful load
electric circuit
safety current must go through
fuse
magnetic switched which open when circuit is overloaded
circuit breakers
tells you how much energy electrons have coming from a power source
voltage
EQUATION: Ohm's Law
V =
I x R
rate at which electrical energy is used
electrical power
EQUATION:
P =
I x V
more devoid of matter than the best vacuum on earth
interstellar space
a nebula turns into a
globule
a globule turns into either a
planet or star
a red giant turns into a
white dwarf
a white dwarf turns into one of 3 things..
black dwarf, nova, supernova type I
emits pulses of electromagnetic radiation; neutron star
pulsar
first person to do calculations that explained a black hole
Oppenheimer
consumes stars and releases tremendous amounts of energy when its first formed
quasar

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