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प्रश्न
Name a metal that is used as an electron emitter. Give one reason for using this metal.
उत्तर
Thoriated tungsten (tungsten coated with carbon and thorium) is used as an electron emitter. Thoriated tungsten is used since it has a work function of only 2-6 eV and it needs to be heated to only 2000K to emit electrons.
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