Advertisements
Advertisements
प्रश्न
A diode value 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 become more and more positively charged?
Advertisements
उत्तर
No, the cathode does not become more and more positively charged. In the diode circuit, the cathode of the diode valve is always connected to the negative terminal of the battery. So, the battery will supply the electrons to the cathode and the cathode will continuously emit electrons without becoming more and more positively charged.
APPEARS IN
संबंधित प्रश्न
Find the maximum frequency of X-rays produced by 30 kV electrons.
Would you prefer a material with a high melting point or a low melting point to be used as a cathode in a diode?
An isolated metal sphere is heated to a high temperature. Will it become positively charged due to thermionic emission?
Why does thermionic emission not take place in non-conductors?
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 place current decrease, increase or remain the same?
Let i0 be the thermionic current from a metal surface when the absolute temperature of the surface is T0. The temperature is slowly increased and the thermionic current is measured as a function of temperature. Which of the following plots may represent the variation in (i/i0) against (T/T0)?

Answer the following question.
Define the term "Threshold frequency", in the context of photoelectric emission.
The work function of aluminum is 4⋅2 eV. If two photons each of energy 2⋅5 eV are incident on its surface, will the emission of electrons take place? Justify your answer.
If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is (Take h = 6.6 × 10–34 Js)
Emission of electrons by the absorption of heat energy is called ____________ emission.
What do you mean by electron emission? Explain briefly various methods of electron emission.
In which case is electron emission from a metal not known?
Consider Figure for photoemission.

How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.
Give an example each of a metal from which photoelectric emission takes place when irradiated by
- UV light
- visible light.
Name the factors on which photoelectric emission from a surface depends.
