Advertisements
Advertisements
प्रश्न
The anode of a thermionic diode is connected to the negative terminal of a battery and the cathode to its positive terminal.
विकल्प
No appreciable current will pass through the diode.
A large current will pass through the diode from the anode to the cathode.
A large current will pass through the diode from the cathode to the anode.
The diode will be damaged.
Advertisements
उत्तर
No appreciable current will pass through the diode.
If the anode is given a negative potential relative to the cathode, the electrons are pushed back to the cathode. Hence, no current will flow through the diode.
APPEARS IN
संबंधित प्रश्न
Find the maximum frequency of X-rays produced by 30 kV electrons.
Find the (a) maximum frequency and (b) minimum wavelength of X-rays produced by 30 kV electrons.
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?
How will the thermionic current vary if the filament current is increased?
Would you prefer a material with a high work-function or a low work-function to be used as a cathode in a diode?
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?
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)?
Define the term "Threshold frequency", in the context of photoelectric emission.
Answer the following question.
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 ______.
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.
Name the factors on which photoelectric emission from a surface depends.
The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate
- the energy of the incident radiation,
- the maximum kinetic energy of the emitted electron and
- the stopping potential of the surface.
