Name:_____________________________________ Row____ Period ___ Date:________
Cheat sheet for Physics B final exam
Electricity, static:
E=F/q
(Definition of electric field)
k=9x109 Nm2/C2
F=kq1q2/d2
(Force between q1 and q2)
PE=kq1q2/d
(PE of q1 near q2)
E=F/qtest
(Definition of E)
E=kq/d2
(E due to q at a distance d)
V=PE/q
(Definition of Voltage aka Potential)
V=kq/d
(V due to q at a distance d)
Electric Currents:
I=q/t
V=IR
(Ohm’s law)
Req=R1 + R2 + ...
(Series resistors)
R eq =
1
1
R1
+
1
R2
+ ...
(Parallel resistors)
Power
P=IV
P=I2R
P=V2/R
Transformers (Not this year)
Pin=Pout
Magnetism
F=qv×B
(Lorenz Force on a charge)
V1 V2
=
N1 N 2
F=LI×B
V =n
(Lorenz Force on a current)
Δ(BA)
d(BA)
(Faraday’s Law)
or calculus-style: V = n
Δt
dt
Right hand rules:
(1) B around a wire.
(2) B due to loop of wire.
Vibrations
f=1/T
T = 2π
(Frequency and period)
l
g
(Period of a pendulum)
T = 2π m / k (Period of a spring oscillator)
x(t)=Asin(2πft)
(Harmonic motion)
Waves
c=3x108 m/s
(Light speed)
v=343 m/s
(Sound at STP)
v=d/t
(wave speed)
v=λf
Standing waves
λ=2L/1, 2L/2, 2L/3,... (Possible λ in cavity of length L)
f=v/λ=v/(2L), 2v/(2L), 3v/(2L)...
Double slits experiment & diffraction grating
sin(θ)=λ/d
(Not this year)
(Angle of 1st bright fringe)
(3) Lorenz force