1 Answer

Answer :

Thermionic emission occurs in vacuum tubes.

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Description : What are the differences between thermionic emission and evaporation?

Last Answer : Thermionic emission occurs when electron leaves the surface of metals while evaporation occur in liquid when strong electron gain energy and escape the liquid surface in gaseous form

Description : The source of the sun's energy is the process of – (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission

Last Answer : (3) Nuclear fusion Explanation: The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, ... thermonuclear fusion in its core. It is thought that almost all other stars form by this process.

Description : The source of the Sun's energy is the process of – (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission

Last Answer : (3) Nuclear fusion Explanation: Nuclear fusion is a nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. During this process, matter ... fusing nuclei is converted to energy which is released. Fusion is the process that powers active stars.

Description : The basic operating principle of a transformer is attributed to ______________. A. electromagnetic induction B. variance of a conductor in a magnetic field C. mutual reaction D. thermionic emission

Last Answer : Answer: A

Description : The process, whereby electrons gain sufficient energy to be released from the surface of a thin, heated metal plate, is known as _____________. A. photo electric emission B. secondary emission C. thermionic emission D. regressive emission

Last Answer : Answer: C

Description : The method used to produce electron emission in most vacuum tubes is known as ____________. A. photoelectric emission B. secondary electric emission C. cold cathodic electric emission D. thermionic emission

Last Answer : Answer: D

Description : The phenomenon of nuclear fission is opposite to that of (A) Radioactive decay (B) Thermionic emission (C) Nuclear fusion (D) Combustion

Last Answer : (C) Nuclear fusion

Description : The source of the Sun’s energy is the process of (1) Photoelectric emission (2) Nuclear fission (3) Nuclear fusion (4) Thermionic emission

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Description : Define Thermionic emission.

Last Answer : The process by which free electrons are emitted from the surface of a metal when external heat energy is applied is called thermionic emission. Thermionic emission occurs in metals that are heated to a very ... of external energy in the form of heat is supplied to the free electrons in the metals.

Description : List any two applications of thermionic emission.

Last Answer : 1. The components which are made by the process of thermionic emission are used in the electronic devices such as cathode ray tube, radio etc.  2. Thermionic emission are used in a ... , power electronics, x-ray generation, and energy converters from high-temperature sources and solar energy.

Description : Quartz crystal in quartz watches work on the principle called? A. Photoelectric effect B. Stark effect C. Thermionic effect D. Piezo-electric effect (Answer) E. None of these

Last Answer : D. Piezo-electric effect (Answer)

Description : The radiation emitted by a body as a result of its temperature.  a. Blackbody Radiation  b. Thermal Inversion  c. Thermionic Inversion  d. Thermal Radiation

Last Answer : Thermal Radiation

Description : A convection process in which an external device, such as a fan, is used to produce the fluid flow.  a. Forced Convection  b. External Convection  c. Placid Convection  d. Thermionic Convection

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Description : A circuit which develops voltage across the horizontal deflection plates is known as a) Time base generator b) Electron gun c) Thermionic diode d) Zener diode

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Last Answer : The photo-electric effect occurs only when the incident light has more than a certain critical frequency 

Description : Ferromagnets

Last Answer : Ferromagnets Only certain materials, such as iron, cobalt, nickel, and gadolinium, exhibit strong magnetic effects. Such materials are called ferromagnetic, after the Latin word for iron, ... licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

Last Answer : Atrraction  capacity  will  increase  if  supply  current  is  increased.

Last Answer : Temporary magnets are used in loud-speakers,generators, motors.

Last Answer : Main causes of noisy solenoid are strong tendency of fan out of laminations at the end caused by repulsion among magnetic lines of force, uneven bearing surface, caused by dirt or uneven wear between moving and stationary parts.

Last Answer : Core of an electromagnet should have low coercivity, high susceptibility.

Last Answer : Magnetism of a magnet can be destroyed by heating, hammering, by inductive action of another magnet.

Last Answer : The magnetic materials exhibit the property of magnetisation because of spin of nucleus.

Last Answer : The bar magnet has the dipole moment.

Last Answer : The stray line of magnetic flux is defined as a line of magnetic flux which does not follow the designed path.

Last Answer : It assures a position which follows a line of magnetic flux

Last Answer : The initial permeability of an iron rod is the permeability almost in non-magnetised state.

Last Answer : The magnetic reluctance of a material decreases with increasing cross-sectional area of the material.

Last Answer : The magneto-motive force is the sum of all currents embraced by one line of magnetic field.

Last Answer : The uniform magnetic field is the field in which all lines of magnetic flux are parallel and equidistant.

Last Answer : Magnetic moment is a vector quantity.

Last Answer : A keeper is used to provide a closed path for flux.

Description : A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be

Last Answer : A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be M/2.

Last Answer : The retentivity (a property) of material is useful for the construction of permanent magnets.

Last Answer : A permanent magnet attracts some substances and repels others.

Description : If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity

Last Answer : If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity less than that of disc and in the same direction.

Last Answer : The commonly used material for shielding or screening magnetism is soft iron.

Last Answer : The most effective and quickest may of making a magnet from soft iron is by placing it inside a coil carrying current.

Last Answer : The Biot-savart’s law is a general modification of Ampere’s law.

Last Answer : Unit for quantity of electricity is coulomb.

Description : The unit of flux is the same as that of

Last Answer : The unit of flux is the same as that of pole strength.

Description : A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be

Last Answer : A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be 2.4 N.

Description : Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be

Last Answer : Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be 0.1 N.

Last Answer : Susceptibility is positive for ferromagnetic substances.

Last Answer : When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle will depend on the radius of the circle.

Last Answer : One maxwell is equal to 10 webers.

Last Answer : When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon resistance of the coil.

Last Answer : One telsa is equal to 1 Wb/m2

Last Answer : The magnetism left in the iron after exciting field has been removed is known as residual magnetism.

Last Answer : The relative permeability is less than unity is case of diamagnetic materials.