Description : If electrical conductivity increases with the increase of temperature of a substance, then it is a: (1) Conductor (2) Semiconductor (3) Insulator (4) Carborator
Last Answer : (2) Semiconductor Explanation: A solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects
Description : If electrical conductivity increases with the increase of temperature of a substance, then it is a (1) Conductor (2) Semiconductor (3) Insulator (4) Carborator
Last Answer : (2) Semiconductor Explanation: A solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects.
Description : A 'dielectric' is a/an ________________. A. electrical insulator B. current flow C. good conductor D. semiconductor material
Last Answer : Answer: A
Description : In a transistor, the base is _______. (1) an insulator (2) a conductor of low resistance (3) a conductor of high resistance (4) an extrinsic semiconductor
Last Answer : (2) a conductor of low resistance Explanation: A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit.
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 : A pure semiconductor under ordinary conditions behaves like (A) a conductor. (B) an insulator. (C) a magnetic material. (D) a ferro-electric material.
Last Answer : (B) an insulator.
Description : Stilton is a – (1) Semiconductor (2) Insulator (3) Nonconductor (4) Conductor
Last Answer : (1) Semiconductor Explanation: Silicon is a chemical element with the symbol Si and its atomic number is 14. Over 90 percent of the Earth's crust is composed of silicate minerals. Highly purified silicon is used in semiconductor electronics.
Description : Ohm's law is valid in case of – (1) semiconductor (2) conductor (3) superconductor (4) insulator
Last Answer : (2) conductor Explanation: Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. It defines the relationship between the three fundamental, electrical quantities: current, voltage, and resistance.
Description : A doped semiconductor is called : a) Extrinsic b) Intrinsic c) Insulator d) Conductor
Last Answer : b) Intrinsic
Description : Silicon is a (1) Semiconductor (2) Insulator (3) Nonconductor (4) Conductor
Last Answer : Semiconductor
Description : Ohm’s law is valid in case of (1) semiconductor (2) conductor (3) superconductor (4) insulator
Last Answer : conductor
Description : Copper is often used as an electrical conductor because it _______________. A. has high resistance at low temperatures B. has a highly polished surface C. is able to pass current with little opposition D. holds insulation together well
Last Answer : Answer: C
Description : In addition to short circuits and sustained overloads, fuses are likely to blow due to _____________. A. loose fuse clips B. low ambient temperatures C. low contact resistance D. all of the above
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.'
Last Answer : Answer: B
Description : Superconductors are those elements – (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperature (3) Which conduct electricity only at super-high temperature (4) Which conduct electricity only, at super-high temperatures
Last Answer : (2) Whose resistance falls almost to zero at very low temperature Explanation: Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in ... lines from the interior of the superconductor as it transitions into the superconducting state.
Description : Superconductors are those elements (1) Whose conductivity is intermediate between metals and insulators (2) Whose resistance falls almost to zero at very low temperatures (3) which turn into insulators at very low temperatures (4) which conduct electricity only at super-high temperatures
Last Answer : Whose resistance falls almost to zero at very low temperatures
Description : Which of the listed conditions describes the effect on intrinsic semiconductor operation as a result of a temperature increase? A. Additional heat sinks will be required B. Conductivity will increase C. Conductivity will decrease D. Resistivity will increase
Description : A current-carrying conductor making electrical contact with a wiring conduit will be indicated by a _____________. A. high switchboard wattmeter reading B. totally dark switchboard ground detecting light C. low switchboard wattmeter reading D. all of the above
Description : A current-carrying conductor makes accidental contact with a wiring conduit. This will be indicated by a _____________. A. low switchboard wattmeter reading B. high switchboard wattmeter reading C. darkened switchboard ground detecting lamp D. darkened switchboard synchronizing lamps
Description : A current carrying conductor making an electrical contact with a wiring metal conduit is indicated by a _____________. A. low switchboard wattmeter reading B. reading of 1.0 on the power factor meter C. high switchboard voltmeter reading D. totally darkened switchboard ground-detecting light
Last Answer : Answer: D
Description : Solids which conduct electricity at higher temperature but not at lower temperature are called (1) super-conductor (2) metallic-conductor (3) semi-conductor (4) insulator
Last Answer : (3) semi-conductor Explanation: Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures. As temperature increases, the semiconductor material becomes a better and better conductor.
Last Answer : semi-conductor
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 existing resistance of a conductor is dependent upon its length, cross-sectional area, _____________. A. temperature and insulation B. material and insulation C. resistive coefficient and material D. material and temperature
Description : Which of the following principle is used to produce low-temperatures'? (1) Super conductivity (2) Joule-Kelvin effect (3) Thermo-electric effect (4) Adiabatic demagnetization
Last Answer : (4) Adiabatic demagnetization Explanation: Magnetic refrigeration is a cooling technology based on the magnetocaloiic effect. This technique can be used to attain extremely low temperatures, as well as the ... of a suitable material is caused by exposing the material to a changing magnetic field.
Description : Which of the following principle is used to produce ‘low-temperatures’ ? (1) Super conductivity (2) Joule-Kelvin effect (3) Thermo-electric effect (4) Adiabatic demagneti-sation
Last Answer : Adiabatic demagneti-sation
Description : If the loss tangent is very less, then the material will be a a) Conductor b) Lossless dielectric c) Lossy dielectric d) Insulator
Last Answer : b) Lossless dielectric
Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
Description : The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual ... using strip or space heaters D. relieved of all capacitive charge by grounding the conductors
Description : At low temperature, Lead behaves as a (1) Semi conductor (2) Super conductor (3) Insulator (4) Conductor
Last Answer : (2) Super conductor Explanation: Lead exhibit superconducting phase transitions at low temperatures of 7.2 Kelvin. This discovery was made in 1913. At this temperature (known as critical temperature), ... to a different phase of matter; this superconducting phase is described by the BCS theory.
Last Answer : (2) Super conductor Explanation: Lead exhibit super conducting phase transitions at low temperatures of 7.2 Kelvin. This discovery was made in 1913.
Description : At low temperature, Lead behaves as a : (1) Semi conductor (2) Super conductor (3) Insulator (4) Conductor
Last Answer : Super conductor
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
Description : A semiconductor that decreases in resistance with an increase in temperature is known as a _____________. A. resistor B. thermistor C. diode D. thermopile
Description : At very high temperatures, extrinsic semiconductor becomes intrinsic semiconductor because (A) Of drive in diffusion of dopants & carriers. (B) Band to band transition dominates impurity ionization. (C) ... band to band transition. (D) Band to band transition is balanced by impurity ionisation.
Last Answer : At very high temperatures, extrinsic semiconductor becomes intrinsic semiconductor because Impurity ionization dominates band to band transition.
Description : When the current flow through a copper wire increases, its _____________. A. resistance will decrease B. insulation will burn C. temperature will increase D. conductivity will increase
Description : Molten sodium (as a coolant in fast breeder reactor) (A) Can’t attain high temperature at normal pressure (B) Is not at all corrosive, even at a higher temperature (C) Is highly radioactive at elevated temperatures and can cause explosion, when it comes in contact with air or water (D) None of these
Last Answer : (C) Is highly radioactive at elevated temperatures and can cause explosion, when it comes in contact with air or water
Description : Compute the conductivity when the current density is 12 units and the electric field is 20 units. Also identify the nature of the material. a) 1.67, dielectric b) 1.67, conductor c) 0.6, dielectric d) 0.6, conductor
Last Answer : c) 0.6, dielectric
Description : When Arsenic atoms are added Germanium lattice, it becomes a/an - (1) Insulator (2) Superconductor (3) Intrinsic semiconductor (4) Extrinsic semiconductor
Last Answer : (4) Extrinsic semiconductor Explanation: When a peritavalent (donor) impurity, like arsenic, is added to germanium, it will form covalent bonds with thegermanium atoms, leaving 1 electron relatively ... this manner - either with Nor P-type impurities - are referred to as EXTRINSIC semiconductors.
Description : C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because (1) The four bonding electrons in the case of C ... the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Last Answer : (4) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Description : When Arsenic atoms are added to Germanium lattice, it becomes a/an (1) Insulator (2) Superconductor (3) Intrinsic semiconductor (4) Extrinsic semiconductor
Last Answer : Extrinsic semiconductor
Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0°. If you close the circuit breaker at this moment _____________. A. the incoming ... hazardous condition will be created by the incoming machine being at a higher frequency than the bus
Description : What is the thermal conductivity of a perfect heat insulator? (A) Zero (B) One (C) ∞ (D) Between 0 and ∞
Last Answer : (A) Zero
Description : Transformers are used onboard ships with AC generators to _____________. A. change frequency B. increase power output to modulating frequency controllers C. decrease power output to modulating frequency ... D. permit higher voltage for electric motor operation and low voltage for lighting circuits
Description : When testing a capacitor with an analog type ohmmeter, a good capacitor will be indicated when _____________. A. there is no meter deflection B. the meter deflects to a low resistance value and ... deflects to a low resistance value and increases rapidly to a higher value, but stays fairly low
Description : Pressure Cooker cooks faster because (1) boiling point decreases with rise of pressure (2) it cooks the food at low pressure (3) higher temperature is attained for cooking (4) the material of the cooker is a good conductor
Last Answer : (3) higher temperature is attained for cooking Explanation: In pressure cooker boiling point of water increases due to high pressure.
Last Answer : higher temperature is attained for cooking
Description : A wire having very high value of conductance is said to be a. very good conductor b. moderately good conductor c. an insulator d. None
Last Answer : a. very good conductor
Description : Which of the following conditions indicates that a lead-acid battery is being charged too rapidly? A. Sparks occurring at the positive terminal. B. Unusually high electrolyte specific gravity. C. Low plate potentials being developed. D. Excessively high temperatures and gassing rates.
Description : Electrical machinery insulation will break down more rapidly due to _________________. A. low loading of motors and generators B. frequent megger testing C. high temperatures and vibration D. high operating frequencies