Description : Which of the listed pairs of materials make the best insulators? A. dry air and a vacuum B. tin and lead C. doped silicon and germanium D. paper and oil
Last Answer : Answer: D
Description : The 'dielectric constant' is a numerical value indicating the effectiveness of a dielectric material in comparison to that of a standard, which is _______________. A. paper or cloth B. glass or mica C. plastic or Teflon D. dry air or a vacuum
Description : Which of the listed groups of electrical insulation materials is best suited for the highest operating temperatures? A. impregnated cotton and silk B. unimpregnated paper and cotton C. pure glass and quartz D. mica and porcelain with bonding agents
Last Answer : Answer: C
Description : When placed in a magnetic field, which of the materials listed will maintain the highest permeability? A. Glass B. Bakelite C. Soft iron D. Aluminum
Description : Mendeleev proposed the existence of an unknown element that he called eka-aluminum. The element is now called: w) magnesium x) silicon y) gallium z) germanium
Last Answer : ANSWER: C -- GALLIUM
Description : Which of the following materials is a good insulator? A. steel B. aluminum C. glass D. copper
Description : Which of the substances listed can be used to shield sensitive equipment from static magnetic fields? A. Glass B. Mica C. Bakelite D. Permeable iron
Description : What is the name given to a doped germanium crystal with an excess of free holes?
Last Answer : P-type crystal.
Description : In order to obtain p-type germanium it should be doped with a (A) Trivalent impurity. (B) Tetravalent impurity. (C) Pentavalent impurity. (D) Any of the above will do.
Last Answer : (A) Trivalent impurity.
Description : Transistors are made from (a) Plastic (b) metals (c)insulators (d) doped semiconductors
Last Answer : d) doped semiconductors
Description : Tunnel diode is a: a) Power diode b) Has light doping c) Has heavy doping d) Is a reverse recovery diode Ans: C 76.LEDs are fabricated from: a) Silicon b) Germanium c) Si or Ge d) Gallium arsenide
Last Answer : Ans: D
Description : High vacuum diodes, gas-filled diodes, and germanium semiconductor diodes may all be used as _____________. A. potentiometers B. rectifiers C. power sources D. photocells
Last Answer : Answer: B
Description : Most conducting materials such as copper, aluminum, iron, nickel, and tungsten _____________. A. increase in resistance with increased temperature B. increase in resistance with decreased ... C. decrease in resistance with increased temperature D. increase in conductance with increased temperature
Last Answer : Answer: A
Description : Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars? A. A grounded commutator bar B. Using improper carbon brushes C. Aligning the front and rear mica V-rings improperly D. An open circuit in the armature
Description : Which of the listed faults cannot be eliminated, EXCEPT by turning or grinding a commutator with a rigidly supported tool? A. Sparking brushes B. Eccentricity C. High mica D. Blackened commutator
Description : This group of alumino-silicate minerals is widely used in making electrical insulators (1) Bauxite (2) Chrornite (3) Manganese (4) Mica
Last Answer : (4) Mica Explanation: Sheet mica is used principally in the electronic and electrical industries. Its usefulness in these applications is derived from its unique electrical and thermal insulating properties and ... it is a good electrical insulator at the same time as being a good thermal conductor.
Description : This group of alumino-silicate minerals is widely used in making electrical insulators (1) Bauxite (2) Chromite (3) Manganese (4) Mica
Last Answer : Mica
Description : The Vindhyan system of rocks is important for the production of [CDS 2011] (a) precious stones and building materials (b) iron ore and manganese (c) bauxite and mica (d) copper and uranium
Last Answer : Ans: (a)
Description : Which of the following is not a dielectric material? (A) Cotton, silk and paper (B) Asbestos, glass, porcelain and mica (C) Rubber and polymeric resins (D) All refractory materials
Last Answer : Option C
Description : Practical method of improving string efficiency a) Increasing crass arms length b) Using different size of insulators c) Using different insulator materials d) Using of guard rings
Last Answer : Ans: Increasing crass arms length*
Description : Why is silicon and germanium used in semiconductors.pdf?
Last Answer : Feel Free to Answer
Description : Name two elements that find wide application in transistor industry – (1) Silicon and Germanium (2) Carbon and Platinum (3) Iridium and Germanium (4) Tungsten and Platinum
Last Answer : (1) Silicon and Germanium Explanation: A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. Semiconductor material (date first used): the metalloids ... -germanium (1989), the allotrope of carbon graphene (research ongoing since 2004), etc.
Description : Which one of the following is an ohmic conductor? (1) Germanium (2) Silicon (3) Carbon (4) Silver
Last Answer : (4) Silver Explanation: Ohmic conductors are conductors that obey Ohm's law, that is Voltage/Current ratio is constant; in other words, the equation Resistance = Voltage/Current is obeyed. ... s resistance does not change with varying current. Metallic conductors such as silver are Ohmic conductors.
Description : What kind of battery panels are used in some advance satellites? A. Gallium Arsenide solar panel B. Germanium based panels C. Silicon based panels D. Gallium Phosphate solar panel
Last Answer : A. Gallium Arsenide solar panel
Description : why silicon type transistor are more often used than germanium?
Last Answer : because silicon has smaller cutoff current Icbo, small variations in Icbo due to variation in temperature as compared to those in case of germanium.
Description : Why cannot thousands of compounds of Boron or silicon or germanium not possible?
Last Answer : Even though B-B, Si-Si, Ge-Ge bonds exits, these compounds are unstable and very reactive and do not last long.
Description : Give reason: Silicon is used widely even through Germanium is a better semiconductor material.
Last Answer : Silicon is the second most abundantly available material and it can be used at higher temperature. Hence it widely used than Germanium.
Description : Which of the following is not an example of elemental solid dielectric? a) Diamond b) Sulphur c) Silicon d) Germanium
Last Answer : c) Silicon
Description : Metalloids (A) Are good conductor of heat & electricity (B) Act as electron donors with metals & as electron acceptor with non metals (C) Are not necessarily solids at room temperature ... & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
Last Answer : D) Are compounds that exhibit both metallic & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
Description : When a sample of germanium and silicon having same impurity density are kept at room temperature then Resistivity of silicon will be higher than that of germanium, Why?
Last Answer : Ans-The answer is simple. Consider the PN diode for Ge 0.3eV is the breakdown voltage and in the case of Si its 0.7eV since the impurities are added in the same amount the bond due to the other atoms of the Si makes it resistive compared to the Ge.. thats all!
Description : Semiconductor germanium and silicon are (a) Pentavalent (b) trivalent (c) divalent (d) tetravalent
Last Answer : (d) tetravalent
Description : Pure semiconductors silicon and germanium are a) Extrinsic b) Intrinsic c) Insulator d) Diodes
Last Answer : b) Intrinsic
Description : Name two elements that find wide application in transistor industry (1) Silicon and Germanium (2) Carbon and Platinum (3) Iridium and Germanium (4) Tungsten and Platinum
Last Answer : Silicon and Germanium
Last Answer : Silver
Description : ‘Germanium diode knee voltage is lower than silicon diode knee voltage.' Justify.
Last Answer : Justification: The band gap between conduction and valence band for Germanium (0.66eV) is less as compared to Silicon (1.11eV).Hence less energy is required to start conduction in Germanium diode.
Description : The Maximum spectral response of the germanium and silicon is in the (A) infrared region (B) ultraviolet region (C) visible region (D) x-ray region
Last Answer : The Maximum spectral response of the germanium and silicon is in the ultraviolet region
Description : Which of the following elements are used as dopants in silicon or germanium semiconductors? A) Antimony B) Phosphorus C) Arsenic D) All the above
Last Answer : Which of the following elements are used as dopants in silicon or germanium semiconductors? A) Antimony B) Phosphorus C) Arsenic D) All the above
Description : Etched or burned bands on the contact faces of the brushes in a direct current generator can be caused by ____________. A. high mica segments B. copper drag on the commutator C. brushes improperly positioned D. copper embedded in the brushes
Description : In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine ... in an oven at a maximum of 95°C for not over 8 hours D. all of the above
Description : The mica used in the commutators of DC machinery is _____________. A. harder than copper B. softer than copper C. the same hardness as the copper D. softer than copper but wears away at a slower rate
Description : Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air? A. Open the machine on both ends so as to allow the air and dust to escape. B. Be certain that the ... panel. C. Be certain that the air is clean and as dry as possible. D. All of the above.
Description : Optical amplifiers use ____________________-doped glass.
Last Answer : erbium
Description : Which of the listed conditions is an advantage of a PN diode over a vacuum diode? A. Longer life. B. No warm up time. C. Less delicate. D. All of the above.
Description : Does copper clad aluminum spread heat more evenly than other materials?
Last Answer : Copper clad aluminum does offer even heat distribution. Other materials such as stainless steel offer comparable heat spread so it really comes down to personal taste.
Description : Which one of the following materials is useful for making bulb filaments? a. aluminum b. Iron c. Copper d. Tungsten
Last Answer : a. aluminum
Description : The 'dielectric constant' of dry air or a vacuum is _______. A. 1 B. 10 C. 100 D. 1000
Description : The dielectric strength of a vacuum or dry air is approximately ________________. A. 450 volts/inch B. 1000 volts/inch C. 20-kv/inch D. 50-kv/inch
Description : Routine maintenance of dry-type transformers should include ____________. A. cleaning the windings, if accessible, with a vacuum cleaner or very low pressure air B. measuring and recording the winding ... . making sure that the units are close to bulkheads or corners to protect them from damage
Description : Which of the following materials may prove unsuitable for handling acetic acid (glacial & anhydrous) at 40°C? (A) Silicone rubber, teflon, porcelain and wood (B) Nickel, monel, stainless steel and graphite (C) Aluminium, copper, high silicon iron (D) Brass, cast iron, mild steel and tin
Last Answer : (D) Brass, cast iron, mild steel and tin
Description : H2SO4 (< 50% concentration) is corrosive to (A) Aluminium, mild steel, stainless steel, concrete & tin (B) Copper, cast iron & high silicon iron (14% Si) (C) Rubber (butyl and hard), silicone rubber & Teflon (D) Glass, graphite, porcelain & stoneware
Last Answer : (A) Aluminium, mild steel, stainless steel, concrete & tin