Description : The main difference between an electron tube and a transistor is the _____________. A. type of function they can perform B. reaction of electron flow through a gas or vacuum in a transistor C. ... when placed in a tube D. reaction of electron flow through a semiconductor used to form a transistor
Last Answer : Answer: D
Description : What relationship must exist between the electron beam and the traveling wave for bunching to occur in the electron beam of a twt?
Last Answer : The traveling wave must have a forward velocity equal to or less than the speed of the electrons in the beam.
Description : Semiconductors have electron number density of order A. 1024 m-3 B. 1020 m-3 C. 1012 m-3 D. 1023 m-3
Last Answer : 1023 m-3
Description : The electron beam in a CRT is made to sweep from left to right across the screen. What tube element causes this sweeping motion?
Last Answer : The horizontal-deflection plate.
Description : In an electron tube regulator, the electron tube replaces what component?
Last Answer : Variable resistor.
Description : How is the electron beam of a three-cavity klystron accelerated toward the drift tube?
Last Answer : A large negative pulse is applied to the cathode.
Description : What is the most accurate method of determining the condition of an electron tube?
Last Answer : Testing the tube in its circuit
Description : What is the most common cause of electron tube failure?
Last Answer : Open filaments
Description : What is the primary advantage of bulk-effect devices over normal pn-junction semiconductors?
Last Answer : Larger microwave power outputs.
Description : Why is induced draught considered better than the forced draught? a) Because power requirement is high for forced draught b) Maintenance of induced draught fan is costlier c) Forced draught is less efficient d) Forced draught produces less amount of speed of air
Last Answer : Because power requirement is high for forced draught
Description : Electron can exist in the atom but outside the nucleus because a) speed of electron is equal to the speed of light b) speed of electron is more than speed of light c) speed of electron is less than speed of light d) None of these
Last Answer : c) speed of electron is less than speed of light
Description : Which of the following properties distinguish a material as conductor, insulator and semiconductor? a) Free electron charges b) Fermi level after doping c) Energy band gap d) Electron density
Last Answer : c) Energy band gap
Description : When a semiconductor is doped with a P-type impurity, each impurity atom will (A) acquire negative charge. (B) acquire positive charge. (C) remain electrically neutral. (D) give away one electron.
Last Answer : (A) acquire negative charge.
Description : To increase mobility of electron in a given piece of semiconductor (A) Increase overall size of the semiconductor (B) Increase length (C) Increase width (D) Small increase in temperature above room temperature value
Last Answer : To increase mobility of electron in a given piece of semiconductor Small increase in temperature above room temperature value
Description : Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the (A) Less corrosion problems (B) Flexibility possible in the baffle arrangement (C) Low pressure drop (D) High heat transfer co-efficient
Last Answer : (B) Flexibility possible in the baffle arrangement
Description : In a shell and tube heat exchanger, floating head is used for (A) Large temperature differentials (B) High heat transfer co-efficient (C) Low pressure drop (D) Less corrosion of tubes
Last Answer : (A) Large temperature differentials
Description : What is the name given to the semiconductor device that has three or more elements?
Last Answer : Transistor
Description : What semiconductor device produces electrical energy when exposed to light?
Last Answer : Photovoltaic cell.
Description : What does the letter "N" indicate in the semiconductor identification system?
Last Answer : A semiconductor.
Description : What type of rectifier is constructed by sandwiching a section of semiconductor material between two metal plates?
Last Answer : Metallic rectifier.
Description : Conduction in which type of semiconductor material is similar to conduction in a copper wire?
Last Answer : N-type material.
Description : What are the majority carriers in a P-type semiconductor?
Last Answer : Holes.
Description : What type of PN diode is formed by using a fine metal wire and a section of N-type semiconductor material?
Last Answer : Point-contact.
Description : What are the majority carriers in an N-type semiconductor?
Last Answer : Electrons.
Description : What is the name given to a piece of pure semiconductor material that has an equal number of electrons and holes?
Last Answer : Intrinsic.
Description : Name the two types of current flow in a semiconductor.
Last Answer : Electron flow and hole flow.
Description : What is lowest current at which stimulated emission exceeds spontaneous emission in a semiconductor laser called?
Last Answer : Threshold current.
Description : What are the two most common semiconductor materials used in electronic and electro-optic devices?
Last Answer : Silicon and gallium arsenide.
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
Description : Semiconductor LEDs emit incoherent light. Define incoherent light
Last Answer : Light waves that lack a fixed-phase relationship
Description : What are the four most common materials used in semiconductor detector fabrication?
Last Answer : Silicon, gallium arsenide, germanium, and indium phosphide.
Description : What characteristic of a gunn oscillator is inversely proportional to the transit time of the domain across the semiconductor?
Last Answer : The frequency.
Description : The domain in a gallium-arsenide semiconductor has what type of electrical field when compared to the other regions across the body of a semiconductor?
Last Answer : A field of much greater intensity.
Description : The point on the current curve of a gallium-arsenide semiconductor at which it begins to exhibit negative resistance is called what?
Last Answer : Threshold.
Description : What happens to the electrons of a gallium-arsenide semiconductor when they move from the normal low-energy conduction band to the high-energy conduction band?
Last Answer : The electrons become immobile.
Description : What is another name for semiconductor memory chips?
Last Answer : Integrated circuits.
Description : A semiconductor memory consists of what?
Last Answer : hundreds of thousands of tiny electronic circuits etched on a silicon chip
Description : What characteristic of a transistor is varied in a semiconductor-reactance modulator?
Last Answer : Collector-to-emitter capacitance.
Description : Type of lasers that uses a mixture of helium and neon enclosed in glass tube. ∙ A. gas lasers ∙ B. solid lasers ∙ C. semiconductor lasers ∙ D. liquid lasers
Last Answer : A. gas lasers
Description : Double pipe heat exchangers are preferably useful, when (A) High viscosity liquid is to be cooled (B) Requirement of heat transfer area is low (C) Overall heat transfer co-efficient is very high (D) A corrosive liquid is to be heated
Last Answer : (B) Requirement of heat transfer area is low
Description : Function of secondary air in pulverised coal firing is to (A) Transport the coal to the burner (B) Dry the coal (C) Ensure efficient burning of coal around the burner (D) Reduce primary air requirement
Last Answer : (C) Ensure efficient burning of coal around the burner
Description : When compared to incandescent lamps, what is the power requirement of an LED?
Last Answer : Very low.
Description : What basic requirement of a closed-loop system (not present in open-loops) enables present load position to be sensed?
Last Answer : Feedback.
Description : What special requirement is the pulse counting accelerometer designed for?
Last Answer : When digital data is required from an accelerometer.
Description : If the load requirement consists of both positive and negative voltages, what technique is used in the voltage divider to supply the loads from a single voltage source?
Last Answer : The ground (reference point) is placed in the proper point in the voltage divider so that positive and negative voltages are supplied
Description : For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it (A) Occupies smaller space (B) Is more economical (C) Is easy to operate and maintain (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Acetamide is a much weaker base than ammonia. This is because (a) the electron withdrawing effect of the C=O group makes the lone pair of electrons on nitrogen atom less available for protonation. (b) ) ... NH2 group. (d) an H atom from the nitrogen is less easily lost from CH3CONH2 than from NH3.
Last Answer : the electron withdrawing effect of the C=O group makes the lone pair of electrons on nitrogen atom less available for protonation
Description : . Why are coaxial lines more efficient at microwave frequencies than two-wire transmission lines?
Last Answer : The electromagnetic fields are completely confined
Description : Why is class C operation more efficient than class A operation?
Last Answer : The amplifier operates (and therefore uses power) for less time in class C than in class A.
Description : Why does the grid have a greater effect than the plate on electron flo
Last Answer : Because it is closer to the cathode.