In general, the elongation of a segment is equal to its length divided
by the total length
L
and multiplied by the total elongation
d
. Therefore, a
unit length of the bar will have an elongation equal to 1/
L
times
d
.
This
quantity is called the
elongation per unit length
, or
strain
, and is denoted
by the Greek letter
e
(epsilon). We see that strain is given by the equation