University Physics Volume 2

University Physics Volume 2 develops thermodynamics and electromagnetism through sixteen calculus-based chapters. The OpenStax text by William Moebs, Samuel J. Ling, Jeff Sanny, and contributors connects microscopic models, energy and entropy, fields, circuits, induction, and electromagnetic waves. This guide emphasizes system boundaries, symmetry, mathematical representation, and model conditions. Each task asks readers to explain a relationship and check its result rather than substitute numbers without a physical account.

Chapter-wise summaries and study tasks

Chapter 1 Temperature and Heat

Temperature describes thermal state while heat is energy transferred under thermal conditions. The chapter connects thermometers and scales with expansion, heat capacity, phase changes, calorimetry, and transfer mechanisms. Conduction, convection, and radiation represent different processes and may act together. A material’s temperature and the rate at which it exchanges energy are not identical quantities.

Define the system and stage of a process before calculating. Heating within a phase differs from adding energy during a phase transition. Conservation in an ideal calorimetry model also depends on which transfers are included or neglected.

Study task. Build an energy account for a multistage heating or mixing problem. Separate temperature change from phase change and identify a transfer neglected by the ideal model.

Chapter 2 The Kinetic Theory of Gases

Kinetic theory links gas pressure and temperature with molecular motion under a statistical model. Ideal-gas relationships describe aggregate behavior, while velocity distributions and equipartition connect macroscopic quantities with microscopic energy. Mean free path and collisions add a scale for transport. Interactions and finite molecular size explain why an ideal model has limits.

Do not equate temperature with the speed of every molecule. A distribution contains variation, and mass affects speed comparisons under the same temperature. State equilibrium and model assumptions before drawing conclusions from an equation of state.

Study task. Compare two ideal gases at the same temperature using average kinetic energy and a characteristic speed. Explain a condition under which the ideal equation becomes less reliable and what physical effect it neglects.

Chapter 3 The First Law of Thermodynamics

The first law organizes heat, work, and internal-energy change for a defined thermodynamic system. Work can be represented through a pressure–volume process, making the path important even when initial and final states are fixed. Isothermal, adiabatic, constant-pressure, and constant-volume models impose different constraints. Heat capacities connect these conditions with material behavior.

Use the source’s work-sign convention consistently. Internal energy is a state quantity, whereas heat and work describe transfers along a process. A closed cycle can return to the original internal energy while still exchanging heat and delivering net work.

Study task. Analyze two paths between the same states and compare work, heat, and internal-energy change. Sketch a pressure–volume diagram and explain the significance of its enclosed area for a cycle.

Chapter 4 The Second Law of Thermodynamics

The second law constrains processes beyond energy conservation. Engines, refrigerators, reversible ideals, Carnot limits, and entropy connect directionality with thermal interactions. A device can satisfy an energy balance yet fail a second-law requirement. Entropy changes must be assessed for a properly defined system and surroundings, not through a visual impression of disorder alone.

Reversible models establish comparisons, not an assumption that real processes have no losses. Distinguish thermal efficiency from refrigerator performance measures and identify the temperatures and reservoirs involved. A local entropy decrease does not automatically violate the law.

Study task. Evaluate a fictional engine using both energy and entropy accounts. Explain whether an apparently attractive efficiency is compatible with its reservoirs and distinguish a reversible benchmark from actual performance.

Chapter 5 Electric Charges and Fields

Electric charge and field introduce conserved charge, Coulomb interactions, superposition, and continuous charge distributions. Material response helps explain conductors, insulators, and redistribution. A field is defined through the source arrangement; the force on a test charge also depends on its sign and magnitude. Integrating a distribution requires a geometry and source element that match the physical setup.

Field-line drawings summarize direction and pattern, not literal paths or material strands. Symmetry can simplify vector components before integration. Check limiting behavior far from a distribution against an appropriate simpler source.

Study task. Derive the field of a simple symmetric distribution and compare a far-field limit with a point-source expectation. Predict the force on opposite test charges without changing the source field.

Chapter 6 Gauss's Law

Gauss’s law relates electric flux through a closed surface to enclosed charge. Its general validity does not mean every geometry yields a simple field calculation. Symmetry determines whether the field can be taken outside the flux integral in a useful way. Conductors in electrostatic equilibrium provide important applications.

Distinguish the chosen Gaussian surface from a physical material boundary. Zero enclosed charge gives zero net flux but does not require zero field everywhere on the surface. A successful solution explains both the law and the symmetry argument needed to obtain the desired field.

Study task. Choose a Gaussian surface for a symmetric source and justify each simplification of the flux integral. Contrast it with an asymmetric case where the law remains valid but does not directly determine the local field.

Chapter 7 Electric Potential

Electric potential supplies an energy-per-charge description related to the electric field through spatial change. Potential differences connect with work, and point or continuous sources contribute through scalar superposition. Equipotentials help describe geometry. The reference zero is a convention, while a potential difference has physical consequences.

A zero value of potential does not establish zero field. Use the gradient or an appropriate directional relationship rather than infer force from potential magnitude alone. Compare integrating a field along a path with calculating potential from the source, checking consistency where both are practical.

Study task. Calculate potential for a simple source and recover a field component by differentiation. Explain a case where potential vanishes while the field does not, and identify the chosen reference.

Chapter 8 Capacitance

Capacitance relates separated charge with potential difference for a specified geometry and material arrangement. Series and parallel combinations follow from shared electrical quantities. Energy can be described through the capacitor or field, while dielectrics modify the relationship through polarization. A changed dielectric or geometry must be interpreted with the actual electrical constraint.

Holding charge fixed and holding voltage fixed lead to different changes in stored energy. If a source remains connected, its energy exchange belongs in the account. Do not compare formulas without specifying which physical process they represent.

Study task. Compare a dielectric insertion under fixed-charge and fixed-voltage conditions. Track the source where present and explain why the two energy calculations need not have the same result.

Chapter 9 Current and Resistance

Current describes charge transport, and a microscopic view connects it with carrier density and motion. Resistance and resistivity relate response to material and geometry, while Ohm’s law applies under appropriate behavior. Electrical power and superconductivity illustrate different aspects of transport and energy conversion.

Drift speed is not the same as the propagation speed of an electrical change. A component’s current–voltage relationship may vary with conditions, so a constant-resistance model needs justification. Keep charge conservation and energy transfer distinct when explaining a circuit’s operation.

Study task. Relate a hypothetical conductor’s geometry and carrier properties to current and resistance. Compare a fixed-resistance prediction with a temperature-dependent response, identifying which assumption changed.

Chapter 10 Direct-Current Circuits

Direct-current circuits combine sources, internal resistance, resistors, measurement devices, and time-dependent capacitor behavior. Kirchhoff’s rules express charge and energy constraints, while topology determines shared currents or voltages. An ideal emf and a loaded terminal voltage can differ. Meter placement and loading matter to the measurement itself.

Assign directions and signs consistently; a negative current solution can indicate the actual direction rather than an invalid result. RC charging is not a static resistor-only problem. Check initial and long-time limits to interpret the mathematical solution.

Study task. Solve a paper network with a nonideal source and verify its power account. Sketch an RC transient, checking its initial and limiting states and explaining ideal meter placement.

Chapter 11 Magnetic Forces and Fields

Magnetic fields exert forces on moving charges and currents, with direction set by the vector geometry. Circular or helical motion, force on conductors, torque on loops, and the Hall effect connect the model with measurable consequences. The ideal magnetic force on a point charge is perpendicular to its velocity and does not itself change kinetic energy.

Separate a field source from the object responding to it. A current loop can experience torque even when its net translational force vanishes. Drawing directions before using a magnitude expression prevents sign errors, especially for negative charges.

Study task. Analyze a charged particle entering a uniform magnetic field at an angle. Distinguish changes in direction from changes in speed and compare the result with torque on a current loop.

Chapter 12 Sources of Magnetic Fields

Sources of magnetic fields include currents in simple conductors and more general distributions. Biot–Savart integration and Ampère’s law provide related tools whose convenience depends on geometry. Parallel currents, loops, solenoids, and magnetic materials connect local sources with large-scale response. Material magnetization is not identical to an external free-current description.

Symmetry is a reason for simplifying an integral, not a decorative observation after the calculation. Specify current direction and the path or source element. Check a limiting case or compare two applicable methods to test the result.

Study task. Derive a field for a suitable symmetric current arrangement and justify the simplification. Compare a geometry where direct integration is preferable and explain why Ampère’s law alone does not supply the local field immediately.

Chapter 13 Electromagnetic Induction

Electromagnetic induction relates changing magnetic flux with emf. Flux can change through field strength, area, orientation, or motion, and Lenz’s law sets a response consistent with the change. Motional emf, generators, and eddy-current effects apply these ideas in different configurations. A voltage does not imply a current without an appropriate circuit path.

Trace the energy input as well as direction. An induced current’s magnetic effect can oppose motion, connecting electrical output with required mechanical work. Keep the original field, flux change, and induced response separate in the explanation.

Study task. Compare a moving conductor with a stationary loop in a changing field. Determine the induced direction from the flux change and identify the source of energy for any resulting dissipation.

Chapter 14 Inductance

Inductance relates current change with linked flux and emf, including mutual and self effects. Magnetic energy belongs in a circuit’s energy account, while RL and LC models introduce characteristic time behavior. An inductor can oppose a change in current without requiring current to be permanently zero. Coupled circuits require attention to orientation and sign conventions.

Initial and limiting conditions expose whether a solution fits the modeled switching event. Stored energy can move among fields or be dissipated, depending on the circuit. State idealizations before interpreting a lossless oscillation as a prediction for a real device.

Study task. Analyze an ideal RL transient and an LC energy exchange. Check initial conditions and track stored versus dissipated energy, explaining what changes when resistance is included.

Chapter 15 Alternating-Current Circuits

Alternating-current analysis compares sinusoidal responses through amplitude, phase, impedance, and frequency. Resistors, capacitors, and inductors contribute differently, with series RLC circuits illustrating resonance and power relationships. Phasors are representations of an assumed steady sinusoidal regime rather than a replacement for every transient analysis.

Peak and rms values must be distinguished, and average power depends on phase as well as magnitudes. A resonance claim needs a defined observable and losses. Use limiting low- and high-frequency behavior to check whether the impedance and current predictions make physical sense.

Study task. Analyze a paper RLC circuit across several frequencies. Compare phase, current, and average power, stating whether given voltages are peak or rms and checking a limiting-frequency case.

Chapter 16 Electromagnetic Waves

Maxwell’s equations unify electric and magnetic behavior and support electromagnetic-wave propagation. Changing fields and displacement current complete relationships that static models alone cannot capture. Wave energy, intensity, momentum, and radiation pressure connect field quantities with observable transfer. The spectrum organizes frequencies without creating sharp physical divisions between all bands.

A wave model must distinguish frequency, wavelength, and propagation speed. Energy transport is not the same quantity as a field amplitude, though they are related under the model. Compare source, propagation, and interaction rather than treating a wave equation as a full explanation of every material response.

Study task. Relate electric and magnetic amplitudes for an ideal wave and calculate a corresponding energy-transfer quantity. Explain which assumptions are required and what changes when propagation occurs in a material.

How to study this book

1. Define the system, geometry, path, surface, and sign convention before selecting an equation.
2. Use calculus to connect local descriptions with global quantities, stating symmetry and boundary assumptions.
3. Check conservation, dimensions, and initial or limiting states independently.
4. Keep state quantities, transfers, and measurement conventions distinct, especially in thermodynamics and AC circuits.
5. Work conceptual questions and derivations alongside numerical problems; use approved laboratory instruction for practical activities.

Questions for reflection

• Which simplification follows from symmetry rather than from the law alone?
• What energy transfer is hidden when the system boundary is drawn too narrowly?
• Which limiting case would expose a mistaken sign or model assumption?

Source edition and coverage

This guide covers all sixteen chapters of OpenStax University Physics Volume 2. Reference appendices and selected answers remain in the source. Circuit and thermal examples are educational models rather than instructions for work on hazardous equipment. These are original study explanations and learning tasks. Read the complete book at the official source.