Physics Flashcards
PV graph for different rxns
isobaric = MOST WORK DONE (biggest area)
ashesion / cohesion
high adhesion = concave
high cohesion = convex
conduction
direct contact between surfaces to transfer heat
convection
transfer of heat by motion of fluid (air, liquid) over material
convection ovens cook faster (use both convection + radiaton)
radiation
transfer of energy by EM waves, can transfer through vacuum
phase change
no change in temp, NRG only to change state
q = mL (L = latent heat of transformation)
sublimation = solid-gas. deposition = gas-solid
isobaric process
pressure constant
the normal PV curve is straight line
W = PV, most work done
isothermal process
temperature constant (internal NRG constant, U = 0)
Q = W
isovolumetric process
no volume change, W = 0! (no area)
U = Q
adiabatic process
no heat exchange (Q = 0)
U = W
weight of a given volume using density
Fg = p V g
needed in buoyancy Qs
pressure
ratio of Force:Area, N/m^2 = Pa
P = F/A
F = P x A
hydrostatic pressure, dynamic pressure, atmospheric pressure
absolute pressure = Patm + pgh
guage pressure = difference between absolute and atm pressures
pascal’s principle
- fluid is incompressible, force/pressure is distributed
- hydruolics!!
- VOLUME moved on both sides must be equal, so A1d1 = A2d2
- PRESSURE on both sides must be equal, so F1/A1 = F2/A2
- factor that d1 is larger than d2 is same factor that F2 is larger than F1
- eg. press down 3X as far, create force on other side 3X as powerful
viscosity
resistance of fluid to flow
usually assume it is negligible (need this for Bernoulli)
turbulent flow = occurs past critical speed
flow RATE
- ** flow rate is independent of changes in AREA or SPEED**
- v1A1 = v2A2
- flows faster when area is smaller, but Q will be constant!!
concept of breathing and pressure
venturi flow meter
- as area decreases, v increases, so dynamic P increases
- this means static P decreases – fluid doesn’t push as much, so the height of fluid in the column is LOWER
- referring to h = height of fluid column from static P
charge of electron/proton
1.6 x 10^19 C
either + or -
when placed 1m apart, would 1C of electrons or 1C of protons have greater acceleration?
since both have the same charge (Q), Fe is the SAME
Fnet = Fe
Fnet = m x a
electrons have low mass, therefore higher acceleration
field lines
show direction a test charge would move (+)
from a + point charge = outwards
from a - point charge = inwards
force will be in same direction of field if (+), opp direction if (-)
electric potential energy
- potential energy between 2 charges
- EPE proportional to 1/r for (+) charge
- HIGH EPE for (+) charges brought CLOSER
- HIGH EPE for (-) charges moved FURTHER
electric potential
- ratio of EPE to magnitude of charge: V = U/q
- V = kQ/r
voltage
- potential difference between 2 points at different “r”
- the WORK to move test charge (+ or -) from INIFINITY to a point in E field
- (+) charge will move spontaneously to low EPE (moves away) from high potential to low potential ( ΔV = NEGATIVE)
- (-) charge will move spontaneously to low EPE (moves together) from low potential to high potential ( ΔV = POSITIVE)
- **move from high potential (voltage) to low potential
- think: emf
equipotential lines
ΔV between any 2 points doesn’t depend on path but the difference in voltage (depends on r)
cirlce lines around point charge with same voltage
magnetism
- any moving charge makes a magnetic field
- unit = Testla (T)
diamagnetic
no unpaired e-
no field
repelled by a magnet
paramagnetic
unpaired e-
weakly magnetized in field
dipoles allign
field removed, orient randomly again
ferromagnetic
unpaired e-
strongly magnetized y field
eg. bar magnets, N and S poles
force on a moving charge
F = qvBsinθ
* Force = 0 when θ = 90 or 180
* so any charge moving parallel/antiparallel to magnetic field feels NO FORCE
force on a current carrying wire
*
Fe/E/U/V
summary table:
metallic conductivity
sea of electrons
metals
electrolytic conductivity
concentration of ions in solution
eg. Na+Cl-
current
- I = Q/t
- how much charge is moving past a point in a certain length of time
- flow of POSITIVE CHARGE (actual current is opposite)
conductance
1/resistance
conductance and resistance are inversely proportional
parallel circuit notes:
- pathway with LOW R = HIGH I
- when n# of identical resistors in parallel, Rtotal = R/n
- resistance in parallel DECREASES as you add more resistors (capillary beds)
capacitors
- hold + store charge at a particular Voltage
- C = Q/V in farads
- stronger battery (higher V) = hold more charge now (Q)
- charges it can hold PER Voltage of circuit
- charges on each side must be equal, eg. -5C & +5C
- closer plates = higher capacitance (stronger field)
capacitor VS battery
- 2 lines same length
- doesn’t have energy on its own, needs battery to provide charge
- can only hold charge for limited amount of time
- overall, holds charges away from each other
ammeter
measures current
wired in SERIES
circuit needs to be off
voltmeter
measures voltage DROP between 2 points
wired in PARALLEL
circuit needs to be on
dielectric material
can place in middle of capacitor
INSULATOR
always INCREASES the C by factor of k – C’ = k x C
eg. add dielectric material wehre k=3, Capacitance is now 3X
potential energy stored by capacitor
1/2CV^2 (like KE)
capacitors in series
- 1/C = 1/C1 + 1/C2 …
- reason: charge goes through ALL the distances
- as distance increases, capacitance decreases
- more capacitors in series = lower C total
capacitors in parallel
- charge can build up on all of the plates at the same time
- C = C1 + C2 …
- more charge, higher voltage across each
ohmmeter
measures resistance
circuit should be OFF
transverse VS longitudinal waves
- transverse = oscilation perpendicular to direction of wave
- longitudinal = oscilation parallel
destructive interference
need to be 1/2 wavelength out of phase perfectly cancelling
range of frequency detection by human ear
20-20,000 Hz
above = ultrasonic
below = infrasonic
what determines pitch of sound in a column?
LENGTH OF COLUMN
what is sound
mechanical disturbance of particles in a material along the sound wave’s direction of propagation (longitudinal wave)
speed of sound is fastest in SOLID (higher bulk), slowest in GAS (low bulk)
speed of sound in air
343 m/s
doppler effect
difference between actual and percieved frequencies when source + detector are moving relative to each other
* towards each other = percieve higher freq.
* away from each other = percieve lower freq
* * mnemonic: observer = detector (d), and source (s) — d / s = dom / sub ;)
* ignore the observer +/-, observer NEVER MOVES
* so becomes v / (v +/- Vs)
* subtract source speed when moving towards
intensity threshold of hearing (Io)
1 x 10^-12 W/m^2
sound intensity
I = A^2
I = 1 / d^2
intensity in W/m^2
decibel scale
increase 10dB = 10x loud
increase 20dB = 100x loud
increase 30dB = 1000x loud
if intensity DOUBLES, decibels increase by 6dB
harmonic: strings and open pipe
- n = # of 1/2 wavelengths of the sanding wave supported by the string and open pipe
- n = number of antinodes (string)
- n = # of nodes (open pipe)
strings and open pipes: wavelength and freq. formulas
closed pipe: wavelength and freq. formulas
harmonic: closed pipes
- n = # of 1/4 wavelengths in the pipe
- only ODD integer harmonics (1st, 3rd,)
speed of EM waves in a vaccum/air
3 x 10^8 m/s
visible light spectrum
400-700 nm (x10^-9)
blackbody
absorbs ALL visible light
appears completely black
mirrors
- image on same side as mirror = REAL
- image behind mirror = VIRTUAL
lenses
- image behind lens = REAL
- image on same side of lens = VIRTUAL
- convex lens (converging) = similar to concave mirror
- concave lens (diverging) = similar to convex mirror
rules for both mirrors and lenses
upright = virtual
inverted = real
no image when d = f
multiple lens systems
more lenses = higher power = LOW focal length
m1 x m2 x m3 …
summary chart: mirrors and lenses
refraction
- when light goes into a different medium and changes speed
- as n increases, speed decreases
- enters higher index = bends CLOSE to normal
- angle of refraction measured FROM the normal
critical angle
where angle of refraction = 90 degrees
n1 MUST BE GREATER THAN n2
beyond this, get TIR (fibre optics)
myopia
- nearsighted
- caused by rays of light converging too early, lens of eye is too strong
- want to use DIVERGING (concave) lens to fix
hyperopia
- rays converge too far away, doesn’t hit retina
- use a converging (convex) lens
diagram: myopia and hyperopia
goal: want the rays to intersect at exactly the RETINA
single slit diffraction
central bright fringe = 2x width
m = dark spots
centrepoint where m = 0
double slit diffraction
- all bright spots SAME WIDTH, similar intensities
polarization
- light = TRANSVERSE wave
- direction of wave prop. perpendicular to oscilation
- naturally, direction of oscillation is in all directions, but can polarize the direction of oscillation to one direction (like normal transverse plane wave)
- enantiomers rotate PPL in opposite direcitons
EM Spectrum Order
LIGHT = TRANSVERSE WAVE
radio > micro > IR > visible > UV > X ray > gamma
photoelectric effect
when high frequency light strikes a metal, the metal emits an ELECTRON –> creates current
E = hf (enegy of photons at specifc f)
photon
light quanta (indivisible energy bundle)
proportional to the frequency of light
energy of photons: E = hf
planck’s constant
6.626 x 10^-34 Js
absorption and emission of light
- absorption of NRG = jumps to higher energy level
- emission = when electron falls to a lower energy level, emits a PHOTON
- used in IR spectroscopy, or UV-vis spectroscopy
fluorescence
excite with UV light, electron returns to original state emitting wavelength of higher magnitude (lower NRG) in visible region
mass defect
phenomenon where the actual mass of the nucleus is slightly less than the sum of all the proton and neutrons
due to some matter that’s been converted to ENERGY (nuclear binding energy)
E = mc^2 – nuclear binding energy
nuclear reactions
fusion = small nuclei combine to form large nucleus (eg. sun)
fission = large nucleus splits into smaller nuclei (power plants)
alpha decay
lose 2 protons and 2 neutrons
mass - 4
z - 2 (element changes)
beta minus decay
neutron decays to a proton
emits electron
mass stays the same, Z+1 (element changes)
beta plus decay
proton decays to a neutron
mass stays the same, Z-1 (element changes)
gamma decay
excited nucleus Z emits a RAY
nothing changes, same element + gamma ray
gamma ray = NO MASS, NO CHARGE
electron capture
e- combines with proton to form neutron
mass unchanged, Z-1 (lose proton) so element changes
types of radioactive decays: summary chart
half life
how long it takes for HALF the sample to decay, always constant for a particular material
100% - 50% - 25% - 12.5% - 6.25% - 3.125%
given half life, calculate how long it takes to decay, or how many half lives it takes to get this amount
wavelength of photon
wavelength = h c / E
