30 Questions
What is the phenomenon of ejection of electrons from a metal surface by the application of heat called?
Thermionic emission
Who discovered the phenomenon of thermionic emission?
Edison
What is the unit of the emission constant A in the Richardson-Dushman equation?
ampere per square meter-kelvin squared
What is the term for the current flowing due to thermionic emission?
Thermion current
What is the term for the emitted electrons in thermionic emission?
Thermions
What is the term for the minimum energy required to eject an electron from a metal surface?
Work function
What are the two main categories of electronics?
Valve and Semiconductor Electronics
What is the force that prevents free electrons from escaping the surface of a metal?
Coulombian force
What is the energy level at which the probability of finding an electron is 50%?
Fermi energy level
What is the minimum energy required to remove an electron from the surface of a metal?
Work function
What is the process of electron emission where electrons are emitted due to thermal energy?
Thermionic emission
What is the work function of oxide-coated tungsten?
1 eV
What is the direction of dependence of thermion current density on absolute temperature?
directly proportional to T^2
What is the unit of the Boltzmann constant in the Richardson-Dushman equation?
J/K
What is the exponent of T in the Richardson-Dushman equation?
-2
What is the dependence of thermion current density on emission constant A?
directly proportional to A
What is the kinetic energy of an electron required to overcome the barrier potential energy and come out of the metal surface?
Greater than binding energy
What is the difference between the binding energy and Fermi energy of a metal?
Work function
Which of the following types of electron emission requires heat to emit electrons from a metal?
Thermionic emission
Which type of electron emission does not require an external energy source?
Field emission
What is the energy level below which an electron is bound to the metal surface?
Ground energy level
What is the effect of increasing the absolute temperature on the exponential term of the Richardson-Dushman equation?
The exponential term increases
What is the effect of increasing the emission constant on the current density in the Richardson-Dushman equation?
The current density increases
What is the relationship between the thermion current density and the absolute temperature in the Richardson-Dushman equation?
The thermion current density is proportional to the square of the absolute temperature
What is the physical significance of the Boltzmann constant in the Richardson-Dushman equation?
It relates the thermal energy to the absolute temperature
What is the primary reason why free electrons in a metal experience a barrier on the surface?
Due to the attractive Coulombian force
What is the significance of the Fermi energy level in a metal at 0K temperature?
It is the energy level at which the probability of finding an electron is 50%
What is the difference between the binding energy and the Fermi energy of a metal?
The binding energy is greater than the Fermi energy
What is the work function of a material related to?
The minimum energy required to take out an electron from the surface of the material
What is the process of electron emission in which electrons are emitted due to an applied electric field?
Field emission
Test your knowledge of valve electronics and semiconductor electronics, including concepts such as barrier potential energy, Fermi energy, and free electrons in metals.
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