Pushing the telegraph key completes an electrical circuit that causes an electromagnet coil to click when pulled down, making a dot. Releasing the key causes the coil to clack as the metal strip springs up, making a dash. Operators can differentiate dots from dashes based on the distinct click and clack sounds produced when the electromagnet pulls and releases the metal strip.

2. How do you send message
with an Electromagnet?

10.  pushing down the telegraph key completes the
electrical circuit from the key to one end of the coil
and from the other end of the coil to one end of
the battery and from the other terminal of the
battery back to the other side of the key.
Now the sounder magnet should pull down the
metal strip and make a CLICKING sound. When
you release the key, the metal strip should spring
upwards and make a CLACKING sound.

11.  the difference between the dots and the dashes of
the Morse code by learning to tell the difference
between the pull-in "CLICK" and the release-
"CLACK".
 The pull-in "CLICK" is the sound the metal strip
makes when it is pulled in by the electromagnet
coil and strikes the nail which is in the center of the
coil.
 The release "CLACK" is the sound that the metal
strip makes when it is no longer pulled by the
electromagnet coil and it moves rapidly upward to
strike the upper nail.
 The Morse Code Characters are called DOTS (or
'dits') and DASHES (or 'dahs') They are made from
the CLICKS and CLACKS