Description : Which of the listed pairs of materials make the best insulators? A. copper and aluminum B. glass and mica C. dry air and a vacuum D. doped silicon and germanium
Last Answer : Answer: B
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
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
Last Answer : Answer: D
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 : Which of the following statements best describes the material known as varnished cambric? A. Felted asbestos sealed with varnish. B. Cotton cloth coated with insulating varnish. C. Rubber ... Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.
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 : 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 : Which of the following material of construction may be recommended by a chemical engineer for handling a gaseous chlorine (dry or wet) stream in a fluid flow system? (A) High silicon iron, silicon rubber ... Mild steel and stainless steel (C) Cast iron, tin and aluminium (D) Copper, nickel and Monel
Last Answer : (A) High silicon iron, silicon rubber, Kel-F and Teflon
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 : 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 : 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 : 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 : 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 : Tin base and lead base alloys are used for bearing materials. Tin compared to lead has lower (A) Price (B) Corrosion resistance (C) Thermal conductivity (D) Abundant availability
Last Answer : (D) Abundant availability
Description : The 'dielectric constant' of dry air or a vacuum is _______. A. 1 B. 10 C. 100 D. 1000
Last Answer : Answer: A
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 : For highly doped diode: a) Zener breakdown is likely to take place b) Avalanche breakdown is likely to take place c) Either (a) or (b) can take place d) Neither (a) nor (b) can take place
Last Answer : Ans: A
Description : For interrupting capacitive currents which Circuit Breaker (CB) is used a) SF6 CB b) Oil CB c) Vacuum CB d) Air blast CB
Last Answer : Ans: Vacuum CB
Description : ____ grippers are used to pick up light weight materials such as paper,cloth etc a.Mechanical grippers b.Adhesive grippers c.Vacuum cup grippers d.Magnetic grippers
Last Answer : b.Adhesive grippers
Description : ____ grippers are used to pick up light weight materials such as paper,cloth etc. (A) Mechanical grippers (B) Adhesive grippers (C) Vacuum cup grippers (D) Magnetic grippers
Last Answer : B
Description : Since fuse elements are made of zinc or any alloy of tin and lead, the melting point of the fuse element must be _____________. A. higher than that of copper B. lower than that of copper C. equal to that of copper D. reached when the conductor it is protecting becomes 'white hot.'
Description : The part of a fuse that melts and opens the circuit is made of _____________. A. copper and antimony B. steel and babbitt C. aluminum or beryllium alloy D. zinc or an alloy of tin and lead
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 : Whic of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torch lights, electric shavers, etc.? (1) Iron and cadmium (2) Nickel and cadmium (3) Lead peroxide and lead (4) Zinc and carbon
Last Answer : (2) Nickel and cadmium Explanation: A rechargeable battery, storage battery, or accumulator is a type of electrical battery. It comprises one or more electrochemical cells, and is a ... sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network.
Description : Which of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torch lights, electric shavers, etc. ? (1) Iron and cadmium (2) Nickel and cadmium (3) Lead peroxide and lead (4) Zinc and carbon
Last Answer : Nickel and cadmium
Description : Drying operation under vacuum is carried out to (A) Dry those materials which have very high unbound moisture content (B) Reduce drying temperature (C) Increase drying temperature (D) Dry materials having high bound moisture content
Last Answer : (B) Reduce drying temperature
Description : Skin depth phenomenon is found in which materials? a) Insulators b) Dielectrics c) Conductors d) Semiconductors
Last Answer : c) Conductors
Description : Magnetic materials (A) provide path to magnetic flux. (B) are good insulators. (C) are semiconductors. (D) None.
Last Answer : (A) provide path to magnetic flux.
Description : Czochralski method is widely used for the growth of crystal of -------------materials. a) Conductors b) semiconductors c) insulator d) conductors & insulators
Last Answer : b) semiconductors
Description : Materials exhibiting zero value of resistivity are known as ______ . (a) conductors (b) semiconductors (c) insulators (d) superconductors
Last Answer : (d) superconductors