Q8 of 49 Page 351

Why does thermionic emission not take place in non-conductors?

No, non-conductors will not take part in thermionic emission due to a high work function. Also, Non-conductors do not have free electrons present on its surface hence no electrons are able to emit from it. Whereas in conductors, due to the presence of free-electrons on its surface it accounts for thermionic emission.


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An isolated metal sphere is heated to a high temperature. Will it become positively charged due to thermionic emission?

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A diode valve is connected to a battery and a load resistance. The filament is heated so that a constant current is obtained in the circuit. As the cathode continuously emits electrons, does it get more and more positively charged?

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The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the plate current decrease, increase or remain the same?

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Why is the linear portion of the triode characteristic chosen to operate the triode as an amplifier?