Assertion: tube's cathode | /r/HasProperty | heated
Facets:
Source sentences:
text: When the cathode is heated, it gives off electrons via thermionic emission.
text: The simplest vacuum tube, the diode, invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode.
text: When the cathode is heated, and a positive voltage is applied to the anode, electrons can flow from the cathode to the anode.