This is just an outline/reminder of what was covered. Come to me with questions if you want it reviewed, especially scientific notation, which we spent very little time on.
High-level view of the electromagnetic spectrum
radio waves
microwaves
infrared
ROYGBIV
red, orange, yellow, green, blue, indigo, and violet, as enumerated by Newton
or just RGB for for those of us that can see the usual three primary colors (many people are red-green colorblind)
to our eyes, yellow can be made as a combination of red and green and cyan can be made as a combination of green and blue, and surprisingly, perhaps, purple can be made as a combination of red and blue
ultraviolet
X-rays
γ-rays (but sometimes photons of all sorts are referred to by the symbol γ)
Definition of an element as number of protons in nucleus (that is what matters most, and everything else follows from that)
definition of isotope (same number of protons, but some other number of neutrons is same element, different isotope)
definition of ion (atom that is not neutral)
more electrons than protons makes a negative ion
fewer electrons than protons makes a positive ion
Constituents of matter
In the nucleus
proton — has a positive charge — +1.6x10^-19 C
neutron — is neutral
Surrounding the nucleus
electron — has a negative charge — -1.6x10^-19 C
usually surrounding the nucleus is the same number of electrons as the number of protons
atoms “like” to be neutral
but atoms aren’t always neutral, for example an electron can be stripped off, see ions above
Units of charge and current
Coulomb, abbreviated C
Ampere, abbreviated A (but watch out for similarity to Å which is a shorthand for 10^-10 m)
1 Coulomb is 1 Ampere of current flowing for 1 second
So you say, “what is the definition of the Ampere?”
And I sing, “We’re going to vent our frustration/If we don’t, we’re going to blow a 50-amp fuse.”
Maybe The Rolling Stones had 50-amp fuses on some of their equipment? At 115V, that would be over 5000 Watts. Seems plausible for a big wall of PA gear or a big wall of lights.
In any case, if The Rolling Stones have intuition for current, I am going to trust that you do too, and I won’t try to define the Ampere, which is the unit of current. It isn’t that hard, but we are getting far afield if we do.
Meaning and implications of n + U → Ba + Kr + 3n
Chain reactions
1, 3, 9, 27, 81, 243, 729, …
Standard scientific units
mass, kilogram, abbreviated kg, the k in kg stands for kilo and means 1000
it is a little annoying that the standard unit for mass is 1000 times some other unit (the gram), but that’s the choice that was made
Why didn’t they just make the gram the standard unit? I dunno. They didn’t.
distance, meter, abbreviated m
watch out, because italic m looks similar and is used as the variable for mass
furthermore non-italic m is also used as the abbreviation for milli, as in millimeter which is abbreviated mm
time, second, abbreviated s
energy, Joule, abbreviated J
1 kg m2/s2 = 1 J
Real-world example of 1 J
100g tangerine dropped from a height of one meter in a gravitational field whose acceleration is approximately 10 m/s2
0.1 kg * 1 m * 10 m/s2 = 1 J
If you dropped the tangerine from two meters, it would hit with an energy of 2 J
Intuitive meaning of units of acceleration: m/s2
m/s per second
Examining units in the equation E= mc2
Example of a 1/5 gram coffee bean converted to energy using E=mc2