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प्रश्न
Name a metal that is used as an electron emitter. Give one reason for using this metal.
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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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