Electromagnetic lenses and telephone: what they have in common

1. Step 1. Electromagnetic lenses — is part of — Electron microscope. They focus the beam.
2. Step 2. Electron microscope — uses — Electromagnet. Magnetic lenses.
3. Step 3. Electromagnet — is part of — Intercom. An electromagnetic lock.
4. Step 4. Intercom — is a kind of — Telephone. An intercom is a simple telephone between the door and the flat.

Open Evothings