Honors Physics
Concept
Force due to
electric charges
Electric fieldpoint charge
Electric Potential
Energy (point
charges)
Electric Potential
Energy (uniform
field)
Potential difference
(voltage)
Charge
Equations
FE = kc∙q1∙q2/r
2
E = kc ∙q/r2
Newtons, kc = 8.99x109 N∙m2/C2
Force divided by q (charge)
Newton/Coulomb N/C
PE = kc∙q1∙q2/r
Force divided by r (distance)
Joules
PE = -q∙E∙d
E = field, d = distance from q
Joules
∆V = - E∙d
Potential Energy divided by q
Volts
charge of electron = 1.60x10-19 C
Coulomb: C, μC
q or Q
Ohm: Ω, mΩ, kΩ
Resistance
R
Current
I = q/t
Voltage
V = I∙R
I = V/R
Power
P = I∙V
P = I2∙R
Cost of Energy
Series Resistance
Parallel Resistance
Name ______________________
Units
$ = kW∙h x hours
Amps: A, mA
R = V/I
Watts: W, kW, MW
energy = power x time (kW∙h) Cost = $/kW∙h
Req = R1 + R2 + R3…
1/Req = 1/R1 + 1/R2 + 1/R3
Volts: V, mV, kV
Ohm, Ω
be sure to calculate inverse
R = Ohm, Ω
Series current
limited by sum of resistors
same current everywhere
Parallel current
sum of currents in each path
each path has its own current
complex circuits
reduce resistors in groups
look for ‘clean’ series or ‘clean’
parallel
Force of magnetism
on a charge
F = B∙q∙v
B = mag field, q = charge, v = speed
Newtons
Force of magnetism
on a wire
F = B∙I∙l
I = current, l = length of wire
Newtons
right hand rule:
thumb in direction of motion
transformers
(induction)
V1/V2 = N1/N2
Longitudinal Waves
Transverse Waves
Simple Harmonic
Motion
fingers in direction of field
V = voltage N = # of turns
force on pos. particle out of palm
1 = primary 2 = secondary
disturbance parallel to direction of wave-energy travel
disturbance perpendicular to direction of wave-energy travel
restoring force is proportional
to distance from equilibrium
T = Period of one cycle
pendulum, mass on a spring
Wave speed
(including sound)
Medium
v = f ∙λ
f = frequency; λ = wavelength
material that transmits the energy of a mechanical wave
Harmonics
multiples of a pitch
Resonance
matching a natural frequency
can cause wild vibration
Doppler Effect
frequency shift due to motion
approaching – higher pitch
Intensity of sound
I = P / 4πr2
P = power; r = radius
Interference of any
waves
constructive, destructive
interference patterns
refraction of Light
Index of refraction n = c/v
c = speed of light; v = speed in medium
reflection of Light
Θ in = Θ out
Lenses & mirrors
Focal point, focal length
Lenses
Electromagnetic
Spectrum
Electromagnetic
Spectrum
Wave-particle
duality
Quantum Energy
(energy of one photon)
deBroglie
wavelength
speed of sound = 340 m/s in air
½ wavelengths matter for resonance
leaving – lower pitch
W/m2 or decibel scale
½ wavelengths matter
Ray diagrams
Converging lens can be used 6 ways, depending on position of object compared to focal length
frequencies from Radio to
gamma rays
radio = 108 Hz
gamma = 1020 Hz
wavelengths from long to very small (10-12m)
photons exhibit wave and
particle characteristics
E = h ∙f
λ = h / m∙v
interference = wave
h = Planck’s constant= 6.63x10-34 J∙s
m∙v = momentum of the object
Energy of a photon given in eV
photoelectric effect = particle
electronVolts: eV
see page 466
de Broglie wavelength: the wavelength of a life-sized object is extremely small and cannot be observed, but the wavelength of an
electron can be observed and is used in Scanning Electron Microscopes. Electrons (and photons) exhibit particle and wave behavior.