Law

Examples of Law in the following topics:

• Gauss's Law

  • Gauss's law is a law relating the distribution of electric charge to the resulting electric field.
  • Gauss's law can be used to derive Coulomb's law, and vice versa.
  • In fact, Gauss's law does hold for moving charges, and in this respect Gauss's law is more general than Coulomb's law.
  • Gauss's law has a close mathematical similarity with a number of laws in other areas of physics, such as Gauss's law for magnetism and Gauss's law for gravity.
  • In fact, any "inverse-square law" can be formulated in a way similar to Gauss's law: For example, Gauss's law itself is essentially equivalent to the inverse-square Coulomb's law, and Gauss's law for gravity is essentially equivalent to the inverse-square Newton's law of gravity.

• A Review of the Zeroth Law

  • Zeroth law justifies the use of thermodynamic temperature, defined as the shared temperature of three designated systems at equilibrium.
  • This law was postulated in the 1930s, after the first and second laws of thermodynamics had been developed and named.
  • It is called the "zeroth" law because it comes logically before the first and second laws (discussed in Atoms on the 1st and 2nd laws).
  • A brief introduction to the zeroth and 1st laws of thermodynamics as well as PV diagrams for students.
  • Discuss how the Zeroth Law of Thermodynamics justifies the use of thermodynamic temperature

• Faraday's Law of Induction and Lenz' Law

  • This relationship is known as Faraday's law of induction.
  • The minus sign in Faraday's law of induction is very important.
  • Lenz' law is a manifestation of the conservation of energy.
  • Lenz' law is a consequence.
  • Express the Faraday’s law of induction in a form of equation

• Hooke's Law

  • Many weighing machines, such as scales, use Hooke's Law to measure the mass of an object.
  • In simple terms, Hooke's law says that stress is directly proportional to strain.
  • Mathematically, Hooke's law is stated as:
  • In such a case, Hooke's law can still be applied.
  • The red line in this graph illustrates how force, F, varies with position according to Hooke's law.

• Introduction and Importance

  • Kirchhoff's circuit laws are two equations first published by Gustav Kirchhoff in 1845.
  • Kirchhoff, rather, used Georg Ohm's work as a foundation for Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL).
  • Kirchhoff's laws are extremely important to the analysis of closed circuits.
  • As a final note, Kirchhoff's laws depend on certain conditions.
  • The voltage law is a simplification of Faraday's law of induction, and is based on the assumption that there is no fluctuating magnetic field within the closed loop.

• The Second Law

  • The second law of thermodynamics deals with the direction taken by spontaneous processes.
  • The law that forbids these processes is called the second law of thermodynamics .
  • Like all natural laws, the second law of thermodynamics gives insights into nature, and its several statements imply that it is broadly applicable, fundamentally affecting many apparently disparate processes.
  • We will express the law in other terms later on, most importantly in terms of entropy.
  • Contrast the concept of irreversibility between the First and Second Laws of Thermodynamics

• Equations of State

  • The ideal gas law is the equation of state of a hypothetical ideal gas (in which there is no molecule to molecule interaction).
  • The ideal gas law is the equation of state of a hypothetical ideal gas (an illustration is offered in ).
  • It was first stated by Émile Clapeyron in 1834 as a combination of Boyle's law and Charles' law.
  • Boyle's law states that pressure P and volume V of a given mass of confined gas are inversely proportional:
  • Therefore, we derive a microscopic version of the ideal gas law

• The Third Law: Symmetry in Forces

  • The third law of motion states that for every action, there is an equal and opposite reaction.
  • These laws form the bases for mechanics.
  • Newton's three laws are:
  • You have undoubtedly witnessed this law of motion.
  • When a swimmer pushes off the wall, the swimmer is using the third law of motion.

• Models, Theories, and Laws

  • The laws of nature are concise descriptions of the universe around us.
  • Laws can never be known with absolute certainty, because it is impossible to perform experiments to establish and confirm a law in every possible scenario without exception.
  • If a good-quality, verifiable experiment contradicts a well-established law, then the law must be modified or overthrown completely.
  • However, the designation law is reserved for a concise and very general statement that describes phenomena in nature, such as the law that energy is conserved during any process, or Newton's second law of motion, which relates force, mass, and acceleration by the simple equation F=ma.
  • The biggest difference between a law and a theory is that a law is much more complex and dynamic, and a theory is more explanatory.

• Momentum, Force, and Newton's Second Law

  • In the most general form, Newton's 2nd law can be written as $F = \frac{dp}{dt}$ .
  • This fact, known as the law of conservation of momentum, is implied by Newton's laws of motion.
  • If the particles are numbered 1 and 2, the second law states that
  • Using symbols, this law is
  • So for constant mass, Newton's second law of motion becomes