phototube cathode

例句：

1. 1. The phototube was used in the early televisions.
   光电管在早期的电视机中被使用。
2. 2. The phototube is essential for the operation of the camera.
   光电管对于相机的运行至关重要。
3. 3. The phototube cathode is where light from the bulb falls onto the plate.
   光电管阴极是灯泡发出的光线落在板上的地方。