AP Physics 1 - NGSS Final

Valid Charges

must be multiple of electron charges

Current

flow of freely moving electric charges (electrons or ions)

Conductor

electrons can move freely

Insulator

electrons are fixed in place, can’t move

Semiconductor

Properties of both, can be ‘doped’ to change conductivity

Charging by friction

transfer of electrons, different charges

Charging by contact (conduction)

Directly touching, objects will have different charges at the end

Charging by induction

No contact, attraction of opposite charges and grounding

Contact of two charged conducting spheres

Charges will be evenly split

Polarization

an object attracted to both charges

Coulomb’s Law

F_magnetism = kq1q2/r²

Increase of charge =

increase in force by same factor

Increase of distance =

increase of force by squared factor

E field around a positive charge

Pushes out

E field around a negative charge

Pulls in

Current formula

I = q/T

Resistance formula

R = qL/A

Conventional Current

Positive to negative

Electron Flow

Negative to positive

Sources of DC current:

Batteries, solar cells, DC generators

Sources of AC current:

Outlets, AC generators

Induced electric field

Redistributes charges when electric field is interrupted, acts opposite to original B

Reason for magnetism

Electron motion; spin produces diamagnetism

Ferromagnetism

Aligns exactly

Diamagnetism

Aligns opposite

Paramagnetic

Some/majority will align

Magnetic force on a moving charge formula

F_magnetic = qvB(sin(theta))

Direction of current-induced magnetic field

Right-hand rule (thumb up)

Faraday’s Law of Induction

-N(d/dt)(BAcos(theta))

To induce a current, change the loops

area

Lenz’s Law

Induced B field will oppose the change in magnetic flux

Transformers

changes the voltage, depends on # of coils

Electromagnetic waves

Synchronized electric and magnetic waves, do not require medium

Frequency scale (increasing):

Radio, Microwave, Infrared, Visible, Ultraviolet, X-Ray, Gamma

Doppler’s Effect

Apparent change in frequency of waves cause by motion

Sonic boom

Sound associated with shock waves when an object travels faster than the speed of sound

Resonance

Increased amplitude when the applied force frequency is close to the natural frequency

Resonance requirement

Must be multiple of natural frequency

Beats

Intensity changes of two resonating sounds interfering (no more than 7 Hz)

Transverse Wave

Not overlapping, particle vibration is

Longitudinal

Overlapping, particle vibration is parallel

Tectonic plate boundary types

Transform, converge, diverge

Crust

Thin, brittle, continental & oceanic

Mantle

Soft solid, hot, dense, Fe, Si, Mg

Plate tectonic are driven by

Convection in the mantle

Outer core

Dense liquid molten rock, mostly Fe, Ni, some Si, gives Earth magnetic field

Inner Core

Solid, dense, very hot, Fe & Ni, pressure keeps from liquefying

Radioactive decay in core causes

Convection currents in mantle

Divergent

Move away, volcanic eruptions, earthquakes

Convergent

Move toward each other, mountan ranges, seafloor trenches

Subduction

One plate slides under the other, continental & oceanic meeting

Shield volcano

Dome-shaped, lava pours from vents

Composite volcano

Cone-shaped, lava erupts from top

Primary

Liquids and solids, slow, first movement in earthquake

Secondary

Solids only, faster, causes more building damage

S-waves bounce ___ the core

off

P-waves bounce ___ the core

through

Star formation creates

shock waves, creating other stars

Shock waves come from

• Wind and UV Radiation

• Supernova explosions

• Collisions of clouds

• Spiral arms of galaxies acting like rotating shock waves

Main Sequence Star Transformation

Nebula → protostar (contracting cloud) → Main sequence start (fusion)

When a Main Sequence star runs out of

hydrogen fuel, it becomes a red giant/supergiant

Higher star mass =

Shorter life

Lower star mass =

Longer life

Black dwarfs cannot

exist yet because the universe is too young

Death of a low/medium star

Outer layers drift (nebula), hot core cools (white dwarf)

Death of a high star

Explode (supernova), leftovers become neutron star, biggest become black hole

Hydrostatic Equilibrium of Stars

Thermal (outward) vs Gravity (inward) - self-regulating

Energy transfer (stars)

Convection and Radiation, some low mass may only have convection

Fusion in Massive Stars

Onion-like, hot/pressure enough for other element fusion

Interior Fusion Order (stars)

Fe → Si → Mg → Ne → O → C → He → H (Reverse Periodic)

Supernova explosions produce

Elements heavier than iron

Big Bang Theory

13.8 billion years ago, all matter originated from a singularity

The universe is constantly

contracting and expanding