AP Physics 2 Laws and Principles

The Bernoulli (Venturi) Effect

At comparable heights, the pressure is lower where flow speed is greater.

Archimedes' Principle

The strength of the buoyant force on an object is equal to the weight of the fluid displaced by the object.

The Second Law of Thermodynamics

Time flows in such a way that ordered systems become disordered (increases entropy), heat always flows from hot to cold, and it's impossible to convert heat completely into work.

The First Law of Thermodynamics

The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed.

The Zeroth Law of Thermodynamics

If two systems are separately found to be in thermal equilibrium with a third system, the first two systems are in thermal equilibrium with each other; that is, all three systems are at the same temperature. Also known as thermodynamic equilibrium.

The Maxwell-Boltzmann Distribution

The distribution of energies (and therefore speeds) of the molecules in a gas or liquid.

The Ideal Gas Law

The relationship PV=nRT, which describes the behavior of an ideal gas

Kinetic Theory of Gases

Develops the concept of temperature as a measurement relating to the "average" Kinetic Energy of molecules in a gas sample and the relationship between temperature, pressure, and volume.

Theory of Relativity Postulate #1

The results of physical experiments will be the same in any non-accelerating reference frames.

Theory of Relativity Postulate #2

The speed of light is constant.

Wave-Particle Duality

Electromagnetic radiation propagates like a wave, but exchanges like a particle.

de Broglie Wavelength

Proved that a particle can behave like a wave with linear momentum.

Davisson and Thomson

Revealed that a stream of electrons exhibited diffraction patterns when scattered by crystals.

Bohr's Explanation on why atoms emit/absorb radiation only at certain discrete wavelengths.

If the electron absorbs energy, it is excited to a higher orbit. After a short time in this excited state, it returns to a lower orbit, thus emitting a photon in the process. Since each allowed orbit (energy level) has a specific radius (and corresponding energy), the photons emitted each jump have only specific wavelengths.

Balmer Formula

Summarizes the visible wavelengths that appear in the emission spectrum of Hydrogen.

Bohr

Discovered where the negative charge (electron) of the atom was.

Rutherford

Discovered where the positive charge (proton) of the atom was.

Photoelectric Effect

Light behaves like a stream of photons.

Compton

Showed light has momentum and can undergo elastic collisions.

Planck

Proposed the idea of light being emitted as individual packets of constant energy called "quanta."

Lenz's Law

The induced current will always flow in the direction that opposes the change in magnetic flux that produced it.

Faraday's Law of Electromagnetic Induction

A current is induced when the magnetic flux passing through the coil/loop of wire changes.

Right-Hand Rule

The direction the particle moving will induce a magnetic force on the particle as long as it is moving perpendicular to the magnetic field. The direction of the magnetic force is always perpendicular to the magnetic field.

Kirchoff's Loop Rule

The voltage drop across any circuit in a complete loop is zero volts.

Kirchoff's Junction Rule

The sum of all current flowing into any junction is equal to the flow out of the junction.

Coulomb's Law

Electric force between charged objects depends on the distance between the objects and the magnitude of the charges (F=K q₁*q₂/r²).

Conservation of Charge

The principle that net electric charge is neither created nor destroyed but is transferable from one material to another.

Conservation of Mass

A principle stating that mass cannot be created or destroyed.

Conservation of Energy

A principle stating that energy cannot be created or destroyed, but can be altered from one form to another.

Total Internal Reflection

The complete reflection of light by the inside surface of a medium (the angle of refraction that becomes 90 degrees-directed along the surface).

Snell's Law

The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for a given frequency (n1sinθ1 = n2sinθ2).

Hyugen's Principle

Every point on a wavefront is in itself the source of spherical wavelets which spread out in the forward direction at the speed of light. The sum of these spherical wavelets forms the wavefront.

Law of Reflection

The angle of incidence is equal to the angle of reflection.