Poetry of Physics and the Physics of Poetry

100 The Poetry of Physics and The Physics of Poetry

the collisions of the electrons with the atoms making up the conductor.
These collisions are also responsible for the resistance of the conductor.
This explains why, for a given current, the amount of heat generated in a
conductor is proportional to its resistance.

96 The Poetry of Physics and The Physics of Poetry

These collisions are also responsible for the resistance of the conductor.

This explains why, for a given current, the amount of heat generated in a

conductor is proportional to its resistance.

Rubbing a rubber rod with a piece of cat's fur and placing a wire

between them is not the most efficient way of creating an electric

current. However, the more efficient methods of producing an electric

current are based on the same idea of creating two polarities of charge,

which a flow of current will neutralize. This is the principle of a battery

with the difference that the separation of the positive and negative charge

is a perpetual process brought about by a chemical reaction. A battery

can be created simply by placing two different metal rods in an acid

solution. When the acid acts upon the metals, it combines chemically

with the metal depositing an excess of electrons on the rods. Since the

acid works on one of the metal rods of the battery faster than the other,

more electrons build on one of the metal rods faster than on the other

rod. If a wire is placed between the two metal rods of the battery an

electric current will flow in order to neutralize the excess of electrons.

However, this flow of electrons activates the battery to continue acting

chemically on the metal rods to produce an excess of charge, which

causes a current flow and so on until the acid finally eats away one of the

rods and then the battery can no longer generate an electric current.

From the study of electric currents generated by devices like the

battery, it was discovered that electric currents exert a force on each

other. This force cannot be attributed to the electric force. Although an

Fig. 11.2

Rubbing a rubber rod with a piece of cat’s fur and placing a wire
between them is not the most efficient way of creating an electric
current. However, the more efficient methods of producing an electric
current are based on the same idea of creating two polarities of charge,
which a flow of current will neutralize. This is the principle of a battery
with the difference that the separation of the positive and negative charge
is a perpetual process brought about by a chemical reaction. A battery
can be created simply by placing two different metal rods in an acid
solution. When the acid acts upon the metals, it combines chemically
with the metal depositing an excess of electrons on the rods. Since the
acid works on one of the metal rods of the battery faster than the other,
more electrons build on one of the metal rods faster than on the other
rod. If a wire is placed between the two metal rods of the battery an
electric current will flow in order to neutralize the excess of electrons.
However, this flow of electrons activates the battery to continue acting
chemically on the metal rods to produce an excess of charge, which
causes a current flow and so on until the acid finally eats away one of the
rods and then the battery can no longer generate an electric current.
From the study of electric currents generated by devices like the
battery, it was discovered that electric currents exert a force on each
other. This force cannot be attributed to the electric force. Although an
electric current involves the flow of electrons, the current in a wire is
actually neutral. As stated earlier, the current is due to the drift of the free
electron in the copper wire in one particular direction. This direction is
actually opposite to the flow of the current. This apparent backward way