flashlight; electric torch
Standard word for a portable battery-powered light. 懐中電灯 is the common modern spelling; 懐中電燈 uses an older form of 灯.
The power went out, so I looked for a flashlight.
A flashlight is essential on mountain paths at night.
The power went out, so I turned on the flashlight.
I lit up the dark room with a flashlight.
The flashlight's batteries ran out.
Flashlights (懐中電灯) are counted with 本 because their long, handle-like shape resembles other slender objects counted this way.