Physics Courses
PHYS 100 - Introduction to Physics (3)
A course for students with relatively weak backgrounds in physics. Kinematics and dynamics; waves; optics; electricity and magnetism. Tutorials will be held in the open workshop format, i.e. unstructured periods each week when teaching assistants are available to answer questions and help with problem assignments. Prerequisite: BC Pre-Calculus 12 (or equivalent) or MATH 100 (may be taken concurrently). BC Physics 11 (or equivalent) is recommended. Students who have obtained a grade of C+ or better in BC high school Physics 12 (or its equivalent) or who have taken any further physics course normally may not take PHYS 100 for credit.
PHYS 101 - Physics for the Life Sciences I (3)
Force and motion, conservation of energy and momentum, fluids, properties of soft matter and thermal physics with applications taken from the life sciences. Prerequisite: BC Principles of Physics 12 or PHYS 100 or equivalent, with a minimum grade of C-. This prerequisite may be waived, at the discretion of the department, as determined by the student's performance on a regularly scheduled PHYS 100 final exam. Please consult the physics advisor for further details. Corequisite: MATH 150 or 151 or 154 or 157; BISC 100 or 101 or 102. Students with credit for PHYS 120, 125 or 140 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 102 - Physics for the Life Sciences II (3)
Waves and optics; electricity and magnetism; modern physics emphasizing radioactivity, with applications taken from the life sciences. Prerequisite: PHYS 101 or 120 or 125 or 140, with a minimum grade of C-. Co-requisite: BISC 100 or 101 or 102. Recommended Corequisites: MATH 152, 155 or 158, PHYS 130. Students with credit for PHYS 121, 126, or 141 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 120 - Mechanics and Modern Physics (3)
A general calculus-based introduction to mechanics. Topics include translational and rotational motion, momentum, energy, gravitation, and selected topics in modern physics. Prerequisite: BC Principles of Physics 12 or PHYS 100 or equivalent, with a minimum grade of C-. This prerequisite may be waived, at the discretion of the department, as determined by the student's performance on a regularly scheduled PHYS 100 final exam. Please consult the physics advisor for further details. Corequisite: MATH 150 or 151 or 154 must precede or be taken concurrently. Students with credit for PHYS 101, 125 or 140 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 121 - Optics, Electricity and Magnetism (3)
A general calculus-based introduction to electricity, magnetism and optics. Topics include electricity, magnetism, simple circuits, optics and topics from applied physics. Prerequisite: PHYS 120 or 125 or 140 (or PHYS 101 with a grade of A or B). Corequisite: MATH 152 or 155 must precede or be taken concurrently. Students with credit for PHYS 102, 126 or 141 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 125 - Mechanics and Special Relativity (3)
An enriched course in mechanics for students with good preparation in physics and mathematics. Special relativity and classical topics such as translational and rotational dynamics and conservation laws will be given a much more sophisticated treatment than in our other first-year courses. Prerequisite: Permission of the department. Co-requisite: MATH 125. Students with credit for PHYS 101, 120 or PHYS 140 may not take PHYS 125 for further credit. Quantitative.
PHYS 126 - Electricity, Magnetism and Light (3)
An enriched course in electromagnetism for students with good preparation in physics and mathematics. Classical topics such as waves, electricity and magnetism, as well as wave particle duality and the birth of Quantum Mechanics, will be given a much more sophisticated treatment than in our other first year courses. Prerequisite: PHYS 125 and permission of the department. Co-requisite: MATH 126. Students with credit in PHYS 102, 121 or 141 may not take this course for further credit. Quantitative.
PHYS 130 - Physics for the Life Sciences Laboratory (2)
Elementary experiments in optics, electricity, mechanics and heat that are designed to augment the general survey course. Corequisite: PHYS 102 should be taken concurrently or may precede; or by permission of the department. Students with credit for PHYS 131 or 141 may not take PHYS 130 for further credit. Quantitative.
PHYS 131 - Physics Laboratory I (2)
Elementary experiments in optics, electricity, and mechanics that are designed to augment the general survey courses. Corequisite: PHYS 121 or 126 should be taken concurrently or may precede; or by permission of the department. Students with credit for PHYS 130 or 141 may not take PHYS 131 for further credit. Quantitative.
PHYS 140 - Studio Physics - Mechanics and Modern Physics (4)
A general calculus-based introduction to mechanics taught in an integrated lecture-laboratory environment. Topics include translational and rotational motion, momentum, energy, gravitation, and selected topics in modern physics. Prerequisite: BC Principles of Physics 12, or equivalent, with a minimum grade of C-. Corequisite: MATH 150 or 151 or 154 must precede or be taken concurrently. Students with credit for PHYS 125 or 120 or 101 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 141 - Studio Physics - Optics, Electricity and Magnetism (4)
A general calculus-based introduction to electricity, magnetism and optics taught in an integrated lecture-laboratory environment. Topics include electricity, magnetism, simple circuits, optics and topics from applied physics. Prerequisite: PHYS 140, with a minimum grade of C-. Corequisite: MATH 152 or 155 must precede or be taken concurrently. Students with credit for PHYS 126 or 121 or 102 may not take this course for further credit. Quantitative/Breadth-Science.
PHYS 190 - Introduction to Astronomy (3)
A survey of astronomy designed primarily for non-science students, with a strong emphasis on active learning outside the classroom. Covers the development of astronomy from the ancient Greeks through the Renaissance, to the modern view of the cosmos as revealed by the scientific method. Topics include naked-eye observation of the night sky, modern observational equipment and techniques, the solar system, stellar evolution, galaxies, the Hubble expansion, the Big Bang, dark matter, dark energy, and startling new theories of the origin and destiny of the universe. Experiential activities involve active observations of the moon, stars and planets, and introductory experiments in some of the basic physics that astronomers use to explore the cosmos. Students who have received credit for PHYS 130, 131 or 141 may not take PHYS 190 for further credit. Quantitative/Breadth-Science.
PHYS 192 - Logarithm and Blues (3)
An exploration of the production, propagation and perception of sound and music from an interdisciplinary perspective. The viewpoints of a professional musician and a physicist will be presented and compared. Topics include elementary acoustics, instrument characteristics, reproduction technologies, tonal anomalies and perception. Breadth-Science.
PHYS 211 - Intermediate Mechanics (3)
An intermediate mechanics course covering kinematics, dynamics, calculus of variations and Lagrange's equations, non-inertial reference frames, central forces and orbits, and rigid body motion. Prerequisite: PHYS 126 or 121 or 141, with a minimum grade of C-. Corequisite: MATH 251; MATH 232 or 240. Recommended: MATH 310 and PHYS 255. Quantitative.
PHYS 221 - Electromagnetics (3)
Electrostatics, magnetostatics, capacitance, inductance, concepts of electric and magnetic fields, Maxwell's equations. Prerequisite: PHYS 126 or 121 or 141; MATH 251, with a minimum grade of C-. Students with credit for PHYS 321 may not take this course for further credit. Quantitative.
PHYS 231 - Physics Laboratory II (3)
Introductory physics laboratory with experiments chosen from mechanics, heat, optics, electricity, magnetism, properties of matter, atomic and nuclear physics, along with lectures on the use of computers for data acquisition and data analysis in the physics laboratory. Prerequisite: PHYS 141 or 131 or 130, with a minimum grade of C-. Recommended co-requisite: PHYS 255. Students with credit for PHYS 234 may not take this course for further credit. Quantitative.
PHYS 233 - Physics Laboratory III (2)
Experiments chosen from among mechanics, heat, optics, electricity, magnetism, properties of matter, atomic and nuclear physics. Engineering Science students will do a selected set of experiments. Prerequisite: PHYS 231 or ENSC 220, with a minimum grade of C-. Quantitative.
PHYS 255 - Vibrations and Waves (3)
The physics of vibrations and waves. Topics include periodic motion, including free and forced oscillations, coupled oscillators, normal modes, and waves in one and higher dimensions. Prerequisite: PHYS 126 or 121 or 141 with a minimum C- grade; or PHYS 101 and 102 with a grade of B or better. Corequisite: MATH 251; MATH 232 or 240. Recommended concurrent: PHYS 211 and MATH 310. Quantitative.
PHYS 285 - Introduction to Relativity and Quantum Mechanics (3)
Special relativity, including relativistic kinematics and dynamics; tests of relativity; matter waves and early quantum models; wave mechanics and its application to molecular, atomic and subatomic systems. Prerequisite: PHYS 255, with a minimum grade of C-. Quantitative.
PHYS 321 - Intermediate Electricity and Magnetism (3)
Development and application of Maxwell's equations in vector differential form. Notation and theorems of vector calculus; electric charge, fields, potentials, capacitance and field energy; conductors; methods for solving electrostatic problems; electric fields in matter; electrical current and the magnetic field; Ampere's law and the vector potential; magnetic fields in matter; electromotive force, electrical resistance, Faraday's law and inductance; Maxwell's correction to Ampere's law and electromagnetic waves. Prerequisite: PHYS 130 or 131 or 141; MATH 252 or 254; MATH 310, with a minimum grade of C-. Students with credit for PHYS 221 may not take this course for further credit. Quantitative.
PHYS 326 - Electronics and Instrumentation (4)
Circuits and circuit theory, passive and active devices, amplifiers, feedback, modern measurement techniques and instrumentation. Prerequisite: PHYS 231 and 255, with a minimum grade of C-. Quantitative.
PHYS 332W - Optics Laboratory (4)
Experiments in optics and modern physics, including diffraction, interference, spectroscopy, lasers and holography. Engineering Science students will do a selected set of experiments. Prerequisite: PHYS 233 and 285, or equivalent, with a minimum grade of C-. Students with credit for PHYS 332 may not take this course for further credit. Writing/Quantitative.
PHYS 335 - Practicum I (3)
This is the first term of work experience in a co-operative education program available to students who are studying physics or related areas, such as biophysics, chemical physics or mathematical physics. Units from this course do not count towards the units required for an 間眅埶AV degree. A course fee is required. This course is evaluated on a pass/withdrawal basis. Prerequisite: Completion of 30 units, with a minimum GPA of 2.75 in the physics program. Students should apply to the department at least one term in advance.
PHYS 336 - Practicum II (3)
This is the second term of work experience in a co-operative education program available to students who are studying physics or related areas, such as biophysics, chemical physics or mathematical physics. Units from this course do not count towards the units required for an 間眅埶AV degree. A course fee is required. This course is evaluated on a pass/withdrawal basis. Prerequisite: PHYS 335 followed by 12 units. A minimum cumulative GPA of 2.75. Students should apply to the department at least one term in advance.
PHYS 344 - Thermal Physics (3)
Heat, temperature, heat transfer, kinetic theory, laws of thermodynamics, entropy, heat engines, applications of thermodynamics to special systems, phase transitions. Prerequisite: PHYS 126 or PHYS 121 or PHYS 141, MATH 251. Quantitative.
PHYS 346 - Energy and the Environment (3)
The physical principles and limitations of renewable energy source utilization and energy conversion. A quantitative introduction to energy conversion and storage systems, including solar power and heating; wind, tidal, geothermal, hydroelectric and nuclear power, hydrogen technology, electrical and mechanical energy storage. Prerequisite: CHEM 120 or 121; PHYS 102 or 121 or 126 or 141; and MATH 155 or 152, with a minimum grade of C-. Quantitative.
PHYS 347 - Introduction to Biological Physics (3)
A physics perspective on cellular structure and composition; random walks and diffusion; properties of fluids, cell motion; entropy and the properties of soft materials; structure and function of proteins; signal propagation in nerves. Prerequisite: Completion of 45 units including CHEM 122, MATH 152 (or 155), PHYS 121 (or 102 or 126 or 141), with a minimum grade of C-. Recommended: BISC 101. Quantitative.
PHYS 365 - Semiconductor Device Physics (3)
Structure and properties of semiconductors, semiconductor theory, theory and operation of semiconductor devices, semiconductor device technology. Prerequisite: PHYS 321 or 221; PHYS 255 or ENSC 380, with a minimum grade of C-. PHYS 321, ENSC 380, and PHYS 365 may be taken concurrently. Recommended: PHYS 285. Students with credit for ENSC 224 may not take PHYS 365 for further credit. Quantitative.
PHYS 384 - Methods of Theoretical Physics I (3)
Applications of mathematical methods in physics, differential equations of physics, eigenvalue problems, solutions to wave equations. Prerequisite: MATH 252 or 254; MATH 310; PHYS 255 or ENSC 380, with a minimum grade of C-. Corequisite: PHYS 211. Quantitative.
PHYS 385 - Quantum Mechanics I (3)
Wave mechanics and the Schroedinger equation, the harmonic oscillator, introduction to Dirac notation, angular momentum and spin, the hydrogen atom, atomic structure, time-independent perturbation theory, atomic spectra, and applications. Prerequisite: MATH 252 or 254; PHYS 285 or ENSC 380 or CHEM 260, with a minimum grade of C-. Corequisite: PHYS 211; MATH 310. Quantitative.
PHYS 390 - Introduction to Astrophysics (3)
Characteristics of stars and their evolution, thermodynamics of stellar interior, origin of the elements, galaxies, cosmology, and origin of the planets. Prerequisite: PHYS 211 and either CHEM 120 or 121, with a minimum grade of C-. Quantitative.
PHYS 395 - Computational Physics (3)
Computer based approaches to the solution of complex physical problems. A partial list of topics includes: Monte-Carlo and molecular dynamics techniques applied to thermal properties of materials; dynamical behavior of conservative and dissipative systems, including chaotic motion; methods for ground state determination and optimization, including Newton-Raphson, simulated annealing, neural nets, and genetic algorithms; the analysis of numerical data; and the use of relevant numerical libraries. Prerequisite: MATH 310, PHYS 211, CMPT 101 or 102, with a minimum grade of C-. Recommended: PHYS 344 or equivalent. Quantitative.
PHYS 413 - Advanced Mechanics (3)
Central forces, rigid body motion, small oscillations. Lagrangian and Hamiltonian formulations of mechanics. Prerequisite: PHYS 384, with a minimum grade of C- or permission of the department. Non-physics majors may enter with MATH 252, 310 and PHYS 211, with a minimum grade of C-. Quantitative.
PHYS 415 - Quantum Mechanics II (3)
Foundations of quantum mechanics, time-dependent perturbation theory, radiation, variational methods, scattering theory, advanced topics, and applications. Prerequisite: PHYS 385 and either PHYS 384 or MATH 314 and 419, with a minimum grade of C-. Quantitative.
PHYS 421 - Electromagnetic Waves (3)
A continuation of PHYS 321: properties of electromagnetic waves and their interaction with matter. Transmission lines and waveguides; antennas, radiation and scattering; propagation of electromagnetic waves in free space and in matter; reflection and refraction at boundaries; polarization, interference and diffraction. Prerequisite: PHYS 321; PHYS 255 or ENSC 380, with a minimum grade of C-. Students with credit for PHYS 324 or 425 may not take PHYS 421 for further credit. Quantitative.
PHYS 431 - Advanced Physics Laboratory I (4)
Advanced experiments in Physics. May include special projects. Prerequisite: PHYS 385 and either PHYS 332 or (PHYS 326 and 465), with a minimum grade of C-. Quantitative.
PHYS 432 - Undergraduate Honours Thesis (6)
Undergraduate research and preparation of an honours thesis over two consecutive semesters. The research project may be in experimental or theoretical physics. Prospective students must obtain agreement of a faculty member willing to supervise the project. Prerequisite: All students interested in taking this course must consult with their faculty supervisor regarding prerequisites.
PHYS 433 - Biological Physics Laboratory (3)
Experiments in biological and soft condensed matter physics including investigation of Brownian motion, molecular order and biophysical forces using techniques such as optical trapping, NMR, spectroscopy and x-ray diffraction. Attention will also be given to more general skills, including experimental design, operating and troubleshooting experimental equipment, data analysis, and the presentation of experimental results. Prerequisite: PHYS 231 or MBB 309; PHYS 344 or PHYS 347 or MBB 323 or CHEM 360, with a minimum grade of C- or permission of the department. Quantitative.
PHYS 435 - Practicum III (3)
This is the third term of work experience in a co-operative education program available to students who are studying physics or related areas, such as biophysics, chemical physics or mathematical physics. Units from this course do not count towards the units required for an 間眅埶AV degree. Students should apply to the department at least one term in advance. A course fee is required. This course is evaluated on a pass/withdrawal basis. Prerequisite: PHYS 336 and 60 units with a minimum cumulative GPA of 2.75.
PHYS 436 - Practicum IV (3)
This is the fourth term of work experience in a co-operative education program available to students who are studying physics or related areas, such as biophysics, chemical physics or mathematical physics. Units from this course do not count towards the units required for an 間眅埶AV degree. Students should apply to the department at least one term in advance. A course fee is required. This course is evaluated on a pass/withdrawal basis. Prerequisite: PHYS 435 followed by 12 units. A minimum cumulative GPA of 2.75.
PHYS 437 - Practicum V (3)
This is an optional fifth term of work experience in a co-operative education program available to students who are studying physics or related areas such as biophysics, chemical physics or mathematical physics. Units from this course do not count towards the units required for an 間眅埶AV degree. A course fee is required. This course is evaluated on a pass/withdrawal basis. Prerequisite: PHYS 436 and a minimum cumulative GPA of 2.75. Students should apply to the department at least one term in advance.
PHYS 445 - Statistical Physics (3)
Postulates of statistical mechanics, partition functions, applications to gases, paramagnetism and equilibrium. Quantum statistics and applications. Prerequisite: PHYS 344 or CHEM 360, with a minimum grade of C-. Recommended: PHYS 385. Quantitative.
PHYS 455 - Modern Optics (3)
Optical physics, including geometrical and physical optics, waves in anisotropic media, coherence, image formation and Fourier optics, guided wave optics and selected advanced topics such as lasers, nonlinear optics, photonics and quantum optics. Prerequisite: PHYS 321 or 221, with a minimum grade of C-. Corequisite: PHYS 385. Quantitative.
PHYS 465 - Solid State Physics (3)
Crystal structure, lattice vibrations and thermal properties of solids, free electron model, band theory, and applications. Prerequisite: PHYS 385, with a minimum grade of C-. Quantitative.
PHYS 485 - Particle Physics (3)
Physics of elementary particles. Symmetries, strong interactions, electromagnetic interactions, weak interaction. Prerequisite: PHYS 385 or CHEM 464, with a minimum grade of C- or permission of the department. Recommended: PHYS 380. Students with credit for NUSC 485 may not take this course for further credit. Quantitative.
PHYS 490 - General Relativity and Gravitation (3)
Gravity and space-time, Einstein's equations and their solution, tests of relativity, black holes, stellar equilibrium and collapse, and cosmological models. Prerequisite: PHYS 285 or MATH 471; PHYS 384, with a minimum grade of C-. Quantitative.
PHYS 492 - Special Topics in Physics (3)
Studies in areas not included within the undergraduate course offerings of the Department of Physics. Prerequisite: Permission of the department.
PHYS 493 - Special Topics in Physics (3)
Studies in areas not included within the undergraduate course offerings of the Department of Physics. Prerequisite: Permission of the department.
PHYS 801 - Student Seminar (1)
Discussion of recent developments in physics, based on student seminars. Attendance is required for all first and second year students proceeding toward MSc or PhD degrees in physics. Course offered regularly.
PHYS 802 - Introduction to Graduate Studies: Research and Teaching in Physics (2)
Basic skills for research and teaching in physics. Required for all students beginning an MSc or PhD degree in physics.
PHYS 810 - Advanced Quantum Mechanics (3)
Advanced non-relativistic and some basic relativistic quantum mechanics: symmetries, Schroedinger/Heisenberg pictures, mixtures, variational and perturbative methods, Dirac equation. Prerequisite: PHYS 415, or equivalent.
PHYS 811 - Topics in Quantum Mechanics (3)
A selection of topics which could include: foundations of quantum mechanics, quantum information theory, Bell's inequality, electron in a magnetic field, formal scattering theory, and others of current interest. Prerequisite: PHYS 810 or equivalent.
PHYS 812 - Introduction to Quantum Field Theory (3)
A first course in relativistic quantum field theory (QFT), mainly quantum electrodynamics (QED). Canonical quantization of the Klein-Gordon, electromagnetic, and Dirac fields; gauge freedom; Feynman diagrams and rules, with applications to scattering cross sections and pair creation; renormalization, with applications to the anomalous magnetic moment of the electron and the Lamb shift. Prerequisite: PHYS 810 or equivalent.
PHYS 821 - Advanced Electromagnetism I (3)
Advanced topics in classical electromagnetic theory: review of Maxwell's equations in free space and in macroscopic media, with applications in contemporary research; relativistic unification of electromagnetism; Lagrangian and Hamiltonian methods in electromagnetism. Prerequisite: PHYS 421 or equivalent.
PHYS 822 - Advanced Electromagnetism II (3)
Advanced topics in electromagnetic waves: propagation and polarization in free space and in macroscopic media, including dispersive and anisotropic media; conducting and dielectric waveguides and resonators; radiation, scattering, and diffraction. Prerequisite: PHYS 421 or equivalent.
PHYS 833 - Biological Physics Laboratory (3)
Experiments in biological and soft condensed matter physics including investigation of Brownian motion, molecular order and biophysical forces using techniques such as optical trapping, NMR, spectroscopy and x-ray diffraction. Attention will also be given to more general skills, including experimental design, operating and troubleshooting experimental equipment, data analysis, and the presentation of experimental results. Prerequisite: PHYS 231 or MBB 309W; PHYS 347 or 344 or MBB 323 or CHEM 360; or permission of the department.
PHYS 841 - Statistical Mechanics (3)
Review of ensembles and thermodynamics, ideal gases, imperfect classical gases, classical and modern theories of phase transitions, renormalization group. Course offered regularly. Prerequisite: PHYS 445 or equivalent.
PHYS 846 - Nonlinear Physics (3)
Nonlinear dynamics and chaos. Pattern formation and an introduction to turbulence. Prerequisite: PHYS 384 or equivalent.
PHYS 847 - Topics in Soft-Condensed Matter and Biological Physics (3)
An introduction to one of several topics in soft-condensed matter and biological physics. Recent versions of this course have focused on polymers, liquid crystals, structures of biological membranes, and cell mechanics. Corequisite: PHYS 841.
PHYS 855 - Modern Optics (3)
Optical physics, including geometrical and physical optics, waves in anisotropic media, coherence, image formation and Fourier optics, guided wave optics and selected advanced topics such as lasers, nonlinear optics, photonics and quantum optics. Prerequisite: Permission of the instructor.
PHYS 861 - Introduction to Solid State Physics (3)
Free electron theory, crystal structure, band theory, Bloch's theorem, electron dynamics, phonons, semiconductors. Course offered regularly. Prerequisite: PHYS 465 or equivalent, and PHYS 415.
PHYS 862 - Solid State Physics II (3)
Special topics in solid state physics such as superconductivity, magnetism, optical properties of solids, electron correlations. Course offered regularly. Prerequisite: PHYS 861.
PHYS 863 - Surface Science, Thin Films and Interfaces (3)
Review of surface science techniques: Auger, XPS electron spectroscopies, low energy electron diffraction (LEED), high energy electron diffraction (RHEED), Scanning tunnelling microscopy (STM). Review of thin film deposition techniques: molecular beam epitaxy of metallic and semiconductor multilayer and superlattice structures. Physics and chemistry of surfaces and interfaces. Course offered occasionally. Prerequisite: PHYS 810, 821, 861 or permission of the department.
PHYS 864 - Structural Analysis of Materials (3)
The application of transmission electron microscopy (TEM) and x-ray diffraction techniques to the study of the structure of materials. Hands-on instruction about the operation of a TEM and x-ray diffractometers is provided. The basic theory required for analyzing TEM and x-ray images and diffraction data is described. Prerequisite: Permission of instructor.
PHYS 871 - Introduction to Elementary Particle Physics (3)
Elementary particle phenomenology; classification of particles, forces, conservation laws, relativistic scattering theory, electromagnetic interactions of leptons and hadrons, weak interactions, gauge theories, strong interactions. Prerequisite: Recommended corequisite: PHYS 812.
PHYS 881 - Special Topics I (3)
PHYS 882 - Special Topics II (3)
PHYS 883 - Special Topics III (3)
PHYS 884 - Special Topics IV (2)
PHYS 885 - Special Topics V (2)
PHYS 886 - Special Topics VI (2)
PHYS 887 - Special Topics VII (1)
PHYS 888 - Special Topics VIII (1)
PHYS 889 - Special Topics IX (1)
PHYS 898 - MSc Thesis (18)
PHYS 899 - PhD Thesis (6)