Bo: Hey guys.
Billy: Hey Bo.
Bobby: Hi Bo.
♫ (lyrics) Flipping Physics ♫
Mr. P.: Ladies and gentle people,
the bell has rung,
therefore class has begun.
Therefore you should be seated in your seat
and ready to review
electricity and magnetism dimensions,
because dimensions are your?
Billy, Bobby, Bo: Friends.
Mr. P.: That's right. Dimensions are your friends.
Here we go.
Bobby, what are the symbol
and dimensions for charge?
Bobby: The symbol for charge is Q.
Generally, a lowercase q for a point charge,
or for a portion of a charge,
and an uppercase Q for a whole charge,
and the dimensions for charge are coulombs,
or capital C.
Mr. P.: Billy, is coulomb a base SI dimension?
Billy: No, coulombs are not a base SI dimension.
Mr. P.: Bo, what are the symbol and dimensions
for electric field?
Bo: The symbol for electric field is an upper case E,
and the dimensions are newtons per coulomb
or volts per meter;
however, we haven't defined volts yet.
Mr. P.: True. Billy, for what is the volt a dimension?
Billy: The volt is, uh,
is the dimension for electric potential difference,
and the symbol for
electric potential difference is delta V.
Oh, and we should also know
that a volt is a joule per coulomb.
Mr. P.: Bo, what are the symbol and dimension
for electric flux?
Bo: Electric flux.
The symbol is that weird uppercase phi,
which looks like an uppercase I with a circle in it
and a subscript of an uppercase E,
to identify it as electric flux.
Oh, and the dimensions for electric flux are
newtons times meters squared over coulombs,
or just volts times meters.
Mr. P.: Very nice, Bo.
Bobby, what are the symbol and dimensions
for capacitance?
Bobby: The symbol for capacitance is
an uppercase C,
and its dimensions are farads,
and a farad is a coulomb per volt,
which reminds me that we shouldn't confuse
the symbol of our capacitance,
with an uppercase C,
with the dimensions for a charge,
coulombs,
which is also, unfortunately,
an uppercase C.
Mr. P.: Billy, what are the symbol and dimensions
for current?
Billy: The symbol for current is an uppercase I,
and its dimensions are amperes, or amps,
which is a coulomb per second,
and it is amperes which are the base SI dimension,
and not coulombs.
Mr. P.: Bobby,
what are the dimensions for resistance?
Bobby: The dimensions for resistance are ohms,
and the symbol for an ohm
is an upside-down horseshoe,
and I know it's upside-down,
because all the luck has fallen out of it.
Billy: And it can't hold soup, for example.
Bobby: Yes, it can't hold soup,
which I guess is unlucky.
Oh, and an ohm is a volt per amp.
Mr. P.: Yes, I'm (laughs) I'm glad you remember.
Bo, what are the symbol and dimensions
for resistivity?
Bo: The symbol for resistivity is a lowercase rho,
which looks like a curly lowercase P,
and shouldn't be confused with
volumetric mass or charge density,
even though it uses the exact same symbol.
The dimensions for resistivity are ohm meters.
Mr. P.: What is the difference between
resistance and resistivity?
Billy?
Billy: Resistivity is a material property,
and resistance is for a specific object,
and it depends on its material
and its geometric shape.
Mr. P.: Bobby, what are the dimensions and symbol
for the time constant?
Bobby: The symbol for the time constant
is a lowercase tau,
not to be confused with torque,
which has the same symbol,
and the dimensions for the time constant
are seconds.
Mr. P.: Billy, what are the symbol and dimensions
for magnetic field?
Billy: The symbol for magnetic field is a B,
and its dimensions are teslas.
Mr. P.: Bo, what is a tesla?
Bo: A tesla?
It's a newton divided by the quantity of amps
times meters.
Mr. P.: And what are the symbol and dimensions
for magnetic flux?
Billy?
Billy: Magnetic flux uses
the same symbol as electric flux,
only with a capital B,
instead of a capital E,
as a subscript,
and the dimensions for magnetic flux
are webers, eh, or Wb.
Mr. P.: And, Bobby, what is a weber?
Bobby: A weber is a tesla times a meter squared.
Mr. P.: Bo, what are the symbol and dimensions
for inductance?
Bo: The symbol for inductance is
an uppercase L,
not to be confused with angular momentum,
and its dimensions are henries,
and a henry is a volt-second per amp.
Mr. P.: Good job, everybody.
You guys have learned really well.
One last time,
dimensions are your?
Billy, Bobby, Bo: Friends.
Mr. P.: Thank you very much
for learning with me today.
I enjoyed learning with you.
Voiceover: Lecture notes are available at
FlippingPhysics.com
Please enjoy lecture notes responsibly.
(man on swing yelling in forward and reverse)