Description : Certain substances loose their electrical resistance completely at super low temperature. Such, substances are called. (1) Super conductors (2) Semi conductors (3) Dielectrics (4) Perfect conductors
Last Answer : (1) Super conductors Explanation: Superconductors are materials that carry electrical current with little or no resistance when cooled, below a certain temperature. While conventional superconductors need to ... temperature superconductors do so above the boiling point of liquid nitrogen (-196 °C).
Description : Super conductors are substances that – (1) offer minimum resistance to flow of electric current (2) conduct electricity at low temperature (3) conduct electricity at high temperature (4) offer high resistance to the flow of electric current
Last Answer : (1) offer minimum resistance to flow of electric current Explanation: A superconductor is a material that can conduct electricity or transport electrons from one atom to another with no ... is released from the material when it reaches the temperature at which it becomes superconductive.
Description : Super conductors are substances that (1) offer minimum resistance to flow of electric current (2) conduct electricity at low temperature (3) conduct electricity at high temperature (4) offer high resistance to the flow of electric current
Last Answer : offer minimum resistance to flow of electric current
Description : The substances which have a large number of free electrons and offer a low resistance are called (a) insulators (b) inductors (c) semi-conductors (d) conductors
Last Answer : (d) conductors
Description : Super conductors are those substances, which (A) Offer no resistance to current flow (B) Conduct electricity at low temperature (C) Offer high resistance to current flow (D) Conduct electricity at high temperature
Last Answer : (A) Offer no resistance to current flow
Description : Materials which can store electrical energy are called (A) magnetic materials. (B) semi conductors. (C) dielectric materials. (D) super conductors.
Last Answer : (C) dielectric materials.
Description : The skin effect is a phenomenon observed in a) Insulators b) Dielectrics c) Conductors d) Semiconductors
Last Answer : c) Conductors
Description : Skin depth phenomenon is found in which materials? a) Insulators b) Dielectrics c) Conductors d) Semiconductors
Description : Both the conduction and displacement current densities coexist in which medium? a) Only conductors in air b) Only dielectrics in air c) Conductors placed in any dielectric medium d) Both the densities can never coexist
Last Answer : c) Conductors placed in any dielectric medium
Description : Semi-conductors have ________ temperature coefficient of resistance. (A) Negative (B) Positive (C) Both positive and negative (D) None of the above
Last Answer : (A) Negative
Description : With rise in temperature the resistance of semi-conductors?
Last Answer : With rise in temperature the resistance of semi-conductors decreases.
Description : The property due to which the resistance of some metal or compound vanishes under certain conditions is (A) Semi conductivity. (B) Super conductivity. (C) Curie point. (D) Magnetostriction.
Last Answer : (B) Super conductivity.
Description : Permanent magnets are made of (A) soft magnetic materials. (B) hard magnetic materials. (C) semi conductors. (D) super conductors.
Last Answer : (B) hard magnetic materials.
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 : Electrical conductivities of semi-conductors are of the order of __________ ohm/cm. (A) 10-3 (B) 103 (C) 10-15 (D) 1015
Last Answer : OptionA
Description : Substances of conductivity between 10–10 10–20 (n m )–1 are: a) Insulators b) Semiconductors c)Super conductors d)Good conductors
Last Answer : a) Insulators
Description : he substances of conductivity of the order of 10–6 – 10–4 (m)–1 are : a) Insulators b) Super conductors c) Semiconductors d)Good conductors
Last Answer : d)Good conductors
Description : The covers of electrical machines are made of (A) soft magnetic materials. (B) hard magnetic materials. (C) super conductors. (D) semiconductors.
Last Answer : (A) soft magnetic materials.
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 : According to widely accepted fluid mosaic model cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several ... domains of the membrane. (d) Many proteins remain completely embedded within the lipid bilayer.
Last Answer : (b) Proteins can also undergo flip-flop movements in the lipid bilayer.
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 : Larger length & diameter water pipes are made by (A) Electrical resistance welding (B) Die casting (C) Semi-centrifugal casting (D) Continuous casting
Last Answer : options A
Last Answer : Option C
Description : For which of the following substances, the resistance decreases with increase in temperature? (1) Pure silicon (2) Copper (3) Nichrome (4) Platinum
Last Answer : (3) Nichrome Explanation: Nichrome has high resistance and it is called a resistor.
Last Answer : Nichrome
Description : The substances which have infinite electrical resistance are called
Last Answer : Insulators
Last Answer : Substances whose specific resistance abruptly decreases at very low temperature are called superconductors.
Description : The removal of paint from electrical equipment, such as generators, should be cautiously undertaken because ____________. A. the mechanical shock of paint removal lessens the dielectric strength ... phase windings frequently become isolated from each other due to dust interference at the terminals
Last Answer : Answer: B
Description : a) Semi-conductors b) Pesticides c) Laser.
Last Answer : a) Semi-conductors: Semiconductor, solid or liquid material, able to conduct electricity at room temperature more readily than an insulator, but less easily than a metal. Such metals as copper, ... the infrared through the X-ray range. Masers are similar devices that produce and amplify microwaves.
Description : __________ is a donor impurity for semi-conductors. (A) Boron (B) Antimony (C) Gallium (D) None of these
Last Answer : (B) Antimony
Description : Give one example of doping which produces p-type of semi-conductors.
Last Answer : Ge doped with Al.
Description : In case of semi-conductors, the ratio of conduction current to displacement current is: A) more than 200 and less than 1000 B) less than 100 but greater than 1/100 C) less than 1/100 D) more than 1000
Last Answer : In case of semi-conductors, the ratio of conduction current to displacement current is: less than 100 but greater than 1/100
Description : The water content in a soil sample when it continues to loose weight without loosing the volume, is called (A) Shrinkage limit (B) Plastic limit (C) Liquid limit (D) Semi-solid limit
Last Answer : Answer: Option A
Description : For which of the following substances, the internal energy and enthalpy are the functions of temperature only (a) any gas (b) saturated steam (c) water (d) perfect gas (e) superheated steam.
Last Answer : Answer : d
Description : What substances are used as conductors ?
Last Answer : Answer : Copper , Aluminum , Peel Leah , Phosphor Prange , Silver , Cheap Tungsten , Nickel etc.
Description : The temperature of boiling water in a steam engine may be high because - (1) there are dissolved substances in water (2) there is low pressure inside the boiler (3) there is high pressure inside the boiler (4) the lire is at very high temperature
Last Answer : (3) there is high pressure inside the boiler Explanation: In the boiler of a steam engine, there is a firebox where coal is shoveled into. The coal is kept burning at a very high temperature, and ... reservoir; the steam is then controlled by a slide valve to move into a cylinder to push the piston.
Description : The temperature of boiling water in a steam engine may be high because : (1) there are dissolved substances in water (2) there is low pressure inside the boiler (3) there is high pressure inside the boiler (4) the fire is at very high temperature
Last Answer : there is high pressure inside the boiler
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 : When insulation failure produces a low resistance current path between two conductors, the resulting condition is known as ____________. A. an open B. a short circuit C. a ground D. a surge
Description : In perfect conductors, the phase shift between the electric field and magnetic field will be a) 0 b) 30 c) 45 d) 90
Last Answer : c) 45
Description : Safety fuse wire used in domestic electrical appliances is made of metal of low (1) Resistance (2) Melting point (3) Specific gravity (4) Conductance
Last Answer : (2) Melting point Explanation: The fuse wire is based on the Joules law of heating which says that when the electric current is allowed to pass through a conductor, the conductor heats up and is ... . For this purpose the material used as fuse wire should have high resistance and low melting point.
Last Answer : Melting point
Description : The electrical conductivity of a __________ decreases with rise in temperature. (A) Metal/alloy (B) Semi-conductor (C) Dielectric (D) None of these
Last Answer : (A) Metal/alloy
Description : Pick out the wrong statement. (A) Lead can creep under its own weight at room temperature (B) The electrical conductivity of gold is considerably reduced by alloying additions due to ... metal (D) With increase in temperature, the electrical conductivity of intrinsic semi-conductor will increase
Last Answer : (C) Recrystallisation temperature decreases with decrease in strain in a cold worked metal
Description : With increase in temperature, the electrical conductivity of a __________ decreases. (A) Semi-conductor (B) Metal or alloy (C) Dielectric (D) None of these
Last Answer : (A) Semi-conductor
Description : With increase in temperature, the electrical conductivity of semiconductors (A) Increases (B) Decreases (C) Remain constant (D) Either (A) or (B), depends on the type of semi-conductor
Last Answer : Option A
Description : . With increase in temperature, the electrical conductivity of semiconductors (A) Increases (B) Decreases (C) Remain constant (D) Either (A) or (B), depends on the type of semi-conductor