Question

What do electricians use to test circuits and what is continuity test?

Answer 1

They use a device called "electric testers" which look similar like screw drivers.

Continuity test is the checking of an electric circuit to see if current flows (that it is in fact a complete circuit). A continuity test is performed by placing a small voltage (wired in series with an LED or noise-producing component such as a piezoelectric speaker) across the chosen path.