G is a constant in nature (also called a universal constant), indicating how strong
a gravitational force exists. In other words, the farther away the objects, the less the
attraction between the objects.
What is statistical mechanics?
Statistical mechanics applies statistics to the field of mechanics—the motion of parti-
cles or objects when subjected to a force. It is used to understand the properties of sin-
gle atoms and molecules of liquids, solids, gases—even the individual quanta of light
that make up electromagnetic radiation—to the bulk properties of everyday materials.
Because statistical mechanics mathematically helps to understand the interactions
between a large number of microscopic elements, it is used in a wide range of fields.
In a way, it is also the “opposite” of thermodynamics, which approaches the same
types of systems from a macroscopic, or large-scale, point of view.
What is Ohm’s Law?
Ohm’s Law is important to the field of electrical studies. It states that direct current
flowing in a conductor is directly proportional to the potential difference between its
ends. First summarized by German physicist Georg Simon Ohm (1789–1854), it is
usually seen in formula form as: VIR(or IV/R), in which Vis the potential differ-
ence (voltage), Iis the current (also written in some texts as i), and Ris the resistance
F=G#Mmr# 2279
MATH IN THE PHYSICAL SCIENCES
Who developed the mathematical equations
that explain electricity and magnetism?O
ne of the major early works about electricity and magnetism was written by
Scottish physicist James Clerk Maxwell (1831–1879), who in 1873 published
A Treatise on Electricity and Magnetism. It contained his mathematically based
theory of the electromagnetic field. These equations, now known as Maxwell’s
equations,include four partial differential equations that provided a basis for the
unification of electric and magnetic fields, the electromagnetic description of
light, and, ultimately, Albert Einstein’s theory of relativity. Although most peo-
ple recognize Isaac Newton’s work on mechanics, few remember Maxwell’s elec-
tromagnetic theories (including the idea of the electromagnetic wave) when it
comes to classical physics. But his theories eventually led to many things we
take for granted today, including radio waves and microwaves.Mm
r^2