College Physics II
College7 units and 54 lessons. Helio talks each one through and draws each step on a board.
Units
Thermodynamics
7 lessons- Kinetic theory of temperature and pressureExplain gas pressure as molecular collisions, use K_avg = (3/2)k_BT and v_rms = √(3k_BT/m), and compare gases at one temperature.
- The ideal gas lawUse PV = nRT = Nk_BT with kelvin temperatures, solve fixed-amount problems with P₁V₁/T₁ = P₂V₂/T₂, and read the isothermal, isochoric and isobaric cases.
- Thermal energy transfer and equilibriumUse heat as energy transferred from hot to cold, name conduction, convection and radiation, and find a final temperature from Q_A + Q_B = 0.
- The first law of thermodynamicsUse ΔU = Q + W with W the work done on the gas, find W = −PΔV, and use ΔU = (3/2)nRΔT to analyse isothermal, adiabatic, isochoric and isobaric processes.
- PV diagrams and workRead states and processes on a P–V diagram, find the work as the area under a curve with the right sign, and use the loop area and ΔU = 0 for a cycle.
- Specific heat and thermal conductivityUse Q = mcΔT for one sample and for mixtures, and use Q/Δt = kAΔT/L to compare how fast energy conducts through a slab.
- Entropy and the second law of thermodynamicsCount microstates to say which outcome is most probable, state the second law for an isolated system and for a part of it, and see why heat flows hot to cold and no engine is perfect.
Electric force, field and potential
8 lessons- Electric charge and electric forceUse Coulomb's law F = k|q₁q₂|/r² for the size of the force between charges, read the direction from the signs, and add the forces from several charges as vectors.
- Conservation of electric charge and the process of chargingSay that charge is conserved and only electrons move, find the charges after friction, conduction and induction, and explain why a charged rod attracts neutral things.
- Fields of point chargesDefine the electric field as force per unit test charge, find the field of a point charge with E = k|Q|/r², use F = qE with the right direction, and read field lines.
- Superposition and uniform fieldsAdd the fields of several charges as vectors, find where a field vanishes, and use the uniform field between parallel plates to find the force and the motion of a charge.
- Electric potential energyFind the electric potential energy of a pair or a group of charges with U = kq₁q₂/r and its signs, relate work to ΔU, and use conservation of K + U for charges released from rest.
- Electric potentialDefine potential as energy per unit charge, find V = kQ/r and add potentials as scalars, use ΔV and U = qV for work and energy, and link E to the slope of V and to equipotentials.
- CapacitorsUse C = Q/ΔV and C = κε₀A/d, find the energy U = ½CΔV², combine capacitors in series and parallel, and say what changes when a dielectric goes in or the plates move apart.
- Conservation of electric energyUse ΔK = −qΔV and the electron volt to find the energy and speed a charge gains moving through a potential difference, in a uniform field or near a point charge.
Electric circuits
9 lessons- Electric CurrentUse I = ΔQ/Δt to find charge from a current, read a current from a charge-time graph, and explain why the current is the same all round a series loop.
- Simple CircuitsSay what a working circuit needs, read and draw circuit symbols, place an ammeter and a voltmeter correctly, use ε = W/q, and predict what a short circuit does.
- Resistance, Resistivity, and Ohm's LawDefine resistance as V/I, apply V = IR to ohmic conductors, find a wire's resistance from R = ρL/A, and read resistance from a V-I graph or a set of measurements.
- Electric PowerUse P = IV and its resistor forms I²R and V²/R, find the energy and cost of running an appliance, and decide which bulb is brighter in series and in parallel.
- Compound Direct Current CircuitsCombine resistors in series and in parallel, reduce a combination circuit step by step, and predict how currents and brightness change when a branch is added or removed.
- Kirchhoff's Loop RuleWrite ΣΔV = 0 around a closed loop with the right signs, solve a single loop for its current, and use it with several sources, a capacitor and ideal meters.
- Kirchhoff's Junction RuleUse ΣI_in = ΣI_out at a junction, and combine it with the loop rule to solve a two-loop circuit for its three branch currents, then check the answer.
- RC circuits: charging and dischargingDescribe the current, charge and voltages in a resistor-capacitor circuit at the start, in between and after a long time, for charging and for discharging, and find the energy involved.
- Time constant and RC graphsFind the time constant τ = RC, use the 63% and 37% marks at one time constant, sketch charging and discharging graphs, and say how changing R, C or ε changes them.
Magnetism and electromagnetism
5 lessons- Magnetic FieldsDescribe a magnetic field and its lines, explain why a compass points north, and use the right-hand rule to give the field direction of a long wire and of a coil.
- Magnetism and Moving ChargesFind the size and direction of the magnetic force on a moving charge, explain why it does no work, and use it to find the radius and period of a charge moving in a circle in a magnetic field.
- Magnetism and Current-Carrying WiresFind the field of a long straight wire, the force on a wire in a field, and the force between two parallel wires, including the direction in each case.
- Magnetic flux and Faraday's lawFind the magnetic flux through a loop with Φ = BA cos θ, use |ε| = |ΔΦ/Δt| to find the emf and current a changing flux induces, and apply it to a sliding rod, a loop crossing a field and a coil next to a changing current.
- Lenz's lawFind the direction of an induced current with the four-step procedure, and explain with energy conservation why it must oppose the change in flux.
Geometric optics
7 lessons- ReflectionApply the law of reflection with angles measured from the normal, locate the virtual image in a plane mirror, and explain diffuse reflection and the turning of a reflected ray.
- Ray diagrams for mirrorsLocate the image in a concave or convex mirror with the three principal rays, and describe it as real or virtual, upright or inverted, enlarged or reduced.
- The mirror equationUse 1/s_o + 1/s_i = 1/f and M = −s_i/s_o with a stated sign convention to find the image distance, size and type for concave and convex mirrors.
- Snell's lawUse the index of refraction n = c/v and Snell's law, with angles from the normal, to find the angle, speed and wavelength of light crossing a boundary, and explain what does not change.
- Total internal reflectionFind the critical angle from sin θ_c = n₂/n₁, say when a ray is totally reflected or escapes, and explain how an optical fiber guides light.
- Ray diagrams for lensesLocate the image formed by a converging or diverging thin lens with the three principal rays, and describe it as real or virtual, upright or inverted, enlarged or reduced.
- The thin lens equationUse 1/s_o + 1/s_i = 1/f and M = −s_i/s_o with a stated sign convention to find the image distance, height and type for converging and diverging lenses.
Waves, sound and physical optics
10 lessons- Properties of Wave Pulses and WavesSeparate the motion of a wave from the motion of the medium, say what sets a pulse's speed, and read a snapshot graph and a time graph of a pulse.
- Periodic WavesRead wavelength, amplitude, period and frequency from graphs, use v = fλ with the medium setting v and the source setting f, and apply intensity I = P/(4πr²) and phase.
- Boundary Behavior of Waves and PolarizationSay whether a reflected pulse is inverted or upright at a fixed end, a free end and a boundary between media, keep the frequency fixed across a boundary, and explain polarization.
- Electromagnetic WavesDescribe an electromagnetic wave, use c = fλ for any band of the spectrum, and use E = hf to compare photon energies and say which radiation can ionize atoms.
- The Doppler EffectExplain with wavefronts why the observed frequency rises when source and observer approach and falls when they recede, with the wave speed and the source's own frequency unchanged.
- Superposition and interferenceAdd displacements where waves overlap, decide loud or quiet from the path difference for two sources, and say that interference redistributes energy instead of destroying it.
- Standing waves in strings and pipesFind the wavelengths and frequencies of a string fixed at both ends, an open pipe and a closed pipe, and say how tension and length change them.
- DiffractionSay when a wave spreads strongly through an opening, and use a sin θ = mλ to find the dark fringes and the width of a single-slit pattern.
- Double-Slit Interference and Diffraction GratingsFind where two slits and a grating put bright fringes with d sin θ = mλ, compute the fringe spacing λL/d, and say what a grating does to white light.
- Thin-Film InterferenceCount the phase shifts of two reflections, use the path 2t and the wavelength λ/n in the film, and find the thicknesses that make a film bright or dark.
Modern physics
8 lessons- Quantum theory and wave-particle dualityFind the energy and momentum of a photon, find the de Broglie wavelength of a particle, and say why wave behaviour shows only when the wavelength matches the openings.
- The Bohr model of atomic structureUse the hydrogen levels E_n = −13.6 eV/n² to find the photon energy and wavelength of any jump, and decide which photons or electrons an atom can absorb.
- Emission and absorption spectraTell continuous, emission and absorption spectra apart, turn each line into an energy-level jump with λ = 1240/ΔE, and explain why dark lines appear at only some of the emission wavelengths.
- Blackbody radiationUse Wien's law and the T⁴ law to say how a hot object's peak colour and total power change with temperature, and explain why Planck needed quantized energy.
- The photoelectric effectUse K_max = hf − φ to find the energy, stopping potential and threshold of photoelectrons, and say how frequency and intensity each change the results.
- Compton scatteringTreat X-ray scattering as a photon-electron collision, find the electron's energy and momentum from the photon's longer wavelength, and use Δλ = (h/mc)(1 − cos θ).
- Fission, fusion, and mass-energyTurn a mass defect into energy with E = Δmc², read the binding-energy-per-nucleon curve to tell which reactions release energy, and balance A and Z in fission and fusion.
- Types of radioactive decayComplete alpha, beta and gamma decay equations by conserving A and Z, and use the half-life to find how much of a sample is left, while keeping one nucleus's randomness apart from a crowd's regularity.
