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Atoms — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsAtoms1 Mark
MCQ
In a vacuum diode, the space around the cathode which is filled with electrons, is called ________:
  • A
    Space charge
  • B
    Electric field
  • C
    Magnetic field
  • D
    Electron cloud
✓

Answer

  1. Space charge

Explanation:

The large number of free electrons emitted from the cathode is builds up at one place near the cathode and forms a cloud of free electrons. Thus cloud of free electrons near the cathode is called space charge. Due to this space charge, the further emitted electrons come back to the cathode hence no virtual emission takes place hence no current flows in the circuit.

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