電源

1. Origins, structure, and basic meaning

• Structure: 電源 (でんげん) is a noun for a source of electrical power or the powered state of a device.
• Basic usage: 電源を切る turns a machine's power off, while 予備の電源に切り替える switches to a backup supply.
  • 作業が終わったら機械の電源を切ってください。 — Turn off the machine's power when the work is complete.
  • 停電の後、予備の電源に切り替えた。 — After the outage, we switched to backup power.

2. Common pitfalls and similar expressions

• Power source and electricity itself
  • 電源 focuses on the supply source or powered state of equipment. 電源を切る means turning a device off, not removing a generating facility.