Advertisements
Advertisements
प्रश्न
How will the thermionic current vary if the filament current is increased?
Advertisements
उत्तर
If the filament current is increased, it will increase the temperature of the cathode (metal) and the cathode will emit more electrons. This will lead to an increase in the number of thermions emitted per unit time. As a result, the thermionic current will increase.
APPEARS IN
संबंधित प्रश्न
The work function of caesium metal is 2.14 eV. When light of frequency 6 × 1014 Hz is incident on the metal surface, photoemission of electrons occurs. What is the
- maximum kinetic energy of the emitted electrons,
- Stopping potential, and
- maximum speed of the emitted photoelectrons?
Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; (–1/3)e]. Why do they not show up in Millikan’s oil-drop experiment?
The work function of the following metals is given : Na 2.75 ev, K = 2.3 eV, Mo = 4.17 eV and Ni = 5.15 eV. Which of these metals will not cause photoelectric emission for radiation of wavelength 3300 Å from a laser source placed 1 m away from these metals? What happens if the laser source is brought nearer and placed 50 cm away?
Would you prefer a material with a high melting point or a low melting point to be used as a cathode in a diode?
Why does thermionic emission not take place in non-conductors?
The anode of a thermionic diode is connected to the negative terminal of a battery and the cathode to its positive terminal.
Define the term "Threshold frequency", in the context of photoelectric emission.
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
The wave associated with a moving particle of mass 3 × 10–6 g has the same wavelength as an electron moving with a velocity 6 × 106 ms–1. The velocity of the particle is
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.
Why do metals have a large number of free electrons?
Define the work function of a metal. Give its unit.
What do you mean by electron emission? Explain briefly various methods of electron emission.
A 150 W lamp emits light of the mean wavelength of 5500 Å. If the efficiency is 12%, find out the number of photons emitted by the lamp in one second.
In which case is electron emission from a metal not known?
Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ration 1 : n then the threshold frequency of the metallic surface is ______.
Give an example each of a metal from which photoelectric emission takes place when irradiated by
- UV light
- visible light.
