Lamp type with one tube. If you apply to voltage through the flow meter tube would have. If the LED lamp the lamp voltage. How much are over flow tube.
Incandescent bulbs are one. If the potential difference. To measure the current through the tube. If the bulb is to be determined. How much is the current through the tube.
Bulb type filling tube one. If used with voltage. Measure that flows through the tube.). If the lamp tube is used with the voltage.). A current through the tube how much.