An invention by carl siemens make the second industrial revolution possible. what was it?
a. an expanded system of telephones
b. insulation for telegraph wires
c. a way to make large quantities of steel in a gas furnace
d. medication from coal tar
which of the following became common in middle-class homes during the second industrial revolution?
a. televisions
b. electric lamps
c. stereos
d. electric typewriters