Intercom
device · 1894 · Electric age
A door entry phone.
What it is made of
- Microphone — has part. A microphone.
- Loudspeaker — has part. A loudspeaker.
- Electromagnet — has part. An electromagnetic lock.
Principles and materials it uses
- Copper — is made of. The wires are copper.
What it is a kind of
- Telephone — is a kind of. An intercom is a simple telephone between the door and the flat.