| Glossary | ||||||||||||||
| magnetic flux
— measure of the strength of a magnetic field through an area. Magnetic flux is measured in tesla square meters (T m2) or webers (Wb). magnetic force — force exerted on an object in a magnetic field. Magnetic force can be either attractive or repulsive depending on both the alignment of the object in the field and the object’s material properties. magnetic poles — two regions in a magnetic field, called magnetic north and south poles, that produce the strongest magnetic force. magnetism — (1) physical phenomenon produced by the motion of electric charge, resulting in attractive and repulsive forces between objects; (2) property of a material or object to attract other objects made out of iron, magnetite, or steel. magnetize — to develop a magnetic field in an object in response to applying an external magnetic field. magnification — change in the apparent size of an object by an optical device or system. magnitude — single number that represents the length, strength, or “size” of a vector without reference to direction. mass — measure of the quantity of matter. Measured in units of kilograms in the International System of Units (SI). English units are slugs (rarely used). mass deficiency — difference between the sum of the mass of nucleons making up a nucleus and the total mass of the nucleus. The mass deficiency is related to binding energy through Einstein’s mass–energy equivalence equation. mass number — total number of protons and neutrons in a nucleus. mass spectrometer — scientific instrument used to measure the masses of individual atoms in a gas using the force exerted on them in a uniform magnetic field. The instrument can be used to identify the elements and isotopes present in a gas. mass–energy equivalence — principle that mass can be converted into energy and vice versa. Represented by the relationship E = mc2. | material strength
— ability of a material or object to sustain force without permanent deformation or breaking. matter — physical substance that has mass and takes up space. Maxwellian distribution — mathematical function that describes the distribution of velocities in an ideal gas in thermal equilibrium. measurement — communication of quantity that includes both a value and a unit. The unit provides a commonly understood interpretation for the value. For example, 2.5 kilograms is a measurement in which 2.5 is the value and kilograms is the unit. mechanical advantage — ratio of the output force to the input force for a machine. mechanical energy — energy that comes from position or motion. Gravitational potential energy, elastic potential energy, rotational energy, and kinetic energy are examples of mechanical energy. microphone — device that transforms the pressure variations in a sound wave into electrical oscillations with the same pattern of variation with time. microscopic — scale that is too small for direct observation with the senses. In physics, this is typically the size of atoms and molecules (or even smaller). microwaves — form of electromagnetic radiation at somewhat higher frequencies than radio waves. mirror — optical device that reflects light. mode — characteristic pattern of resonant vibration of a system which occurs at one of the system’s natural frequencies. model — relationship that connects variables, such as an equation or graph. Models can be quantitative—giving numerical results—or qualitative—giving only a descriptive explanation. mole — quantity of 6.022×1023, which is the number of particles in one mole of matter. Often used when considering the number of atoms or molecules in a quantity of matter. The SI unit for the mole is the mol. moment of inertia — quantity expressing an object’s resistance to change its state of rotation about a particular axis, calculated as the product of mass times the square of the radius from that axis. For a distribution of masses, the moment of inertia is the sum of the individual products of mass times radius squared. Moment of inertia is measured in units of kg m2. | |||||||||||||
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