In case of semi-conductors, the ratio of conduction current to displacement current is: less than 100 but greater than 1/100
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 : The ratio of conduction to displacement current density is referred to as a) Attenuation constant b) Propagation constant c) Loss tangent d) Dielectric constant
Last Answer : c) Loss tangent
Last Answer : In a semiconductor, current conduction is due to Holes and free electrons.
Description : Find the loss tangent of a material with conduction current density of 5 units and displacement current density of 10 units. a) 2 b) 0.5 c) 5 d) 10
Last Answer : b) 0.5
Description : At high frequencies, which parameter is significant? a) Conduction current b) Displacement current c) Attenuation constant d) Phase constant
Last Answer : b) Displacement current
Description : The charge build up in a capacitor is due to a) Conduction current density b) Displacement current density c) Polarisation d) Magnetization
Last Answer : b) Displacement current density
Description : The charge build up in the capacitor is due to which quantity? a) Conduction current b) Displacement current c) Convection current d) Direct current
Last Answer : d) Direct current
Description : When the conduction current density and displacement current density are same, the dissipation factor will be a) Zero b) Minimum c) Maximum d) Unity
Last Answer : d) Unity
Description : The current in a metal at any frequency is due to a) Conduction current b) Displacement current c) Both conduction and displacement current d) Neither conduction nor displacement current
Last Answer : a) Conduction current
Description : For conductors, the free electrons will exist at a) Valence band b) Middle of valence and conduction band c) Will not exist d) Conduction band
Last Answer : d) Conduction band
Last Answer : In conductors conduction of electricity takes place due to movement of electrons only.
Description : Calculate the frequency at which the conduction and displacement currents become equal with unity conductivity in a material of permittivity 2. a) 18 GHz b) 9 GHz c) 36 GHz d) 24 GHz
Last Answer : b) 9 GHz
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 : 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 : 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 : 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 : 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 : 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 : 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 : 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 : Super conductors
Description : With rise in temperature the resistance of semi-conductors?
Last Answer : With rise in temperature the resistance of semi-conductors decreases.
Description : Pick out the wrong statement. (A) Fluid movement under the influence of buoyant forces resulting from change in density takes place in case of natural convection (B) The ratio NNu /NRe . Npr is ... convection to that by conduction (D) The Colburn jH factor for heat transfer is given by Nst Npr
Last Answer : (D) The Colburn jH factor for heat transfer is given by Nst Npr
Description : Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by (A) Eddies current (B) Conduction (C) Convection (D) None of these
Last Answer : (B) Conduction
Description : The leakage current in a pn junction is of the order of
Last Answer : The leakage current in a pn junction is of the order of µA.
Last Answer : The leakage current across a pn junction is due to Minority carriers.
Description : Which of the following statements is not valid in case of conductors in electrostatic fields? A) The static electric field intensity inside a conductor is zero B) The static electric field intensity at ... the surface C) The conductor surface is an equivalent potential surface D) None of the above
Last Answer : Which of the following statements is not valid in case of conductors in electrostatic fields? A) The static electric field intensity inside a conductor is zero B) The static electric field intensity at ... the surface C) The conductor surface is an equivalent potential surface D) None of the above
Description : In case of a ‘High Voltage DC’ transmission, how many minimum conductors are required?
Last Answer : In case of a ‘High Voltage DC’ transmission, how many minimum conductors are required? one
Description : In case of negative work the angle between the force and displacement is -Physics
Last Answer : 180° is the correct answer
Description : In case of simple harmonic motion, displacement is proportional to the (A) Velocity (B) Acceleration (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : B) Acceleration
Description : How much displacement can be generally allowed in sustain case
Last Answer : 5mm
Description : In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate. (A) Geometric (B) Arithmetic (C) Logarithmic (D) Either (A), (B) or (C)
Last Answer : (C) Logarithmic
Description : In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is (A) Linear (B) Hyperbolic (C) Parabolic (D) None of these
Last Answer : (C) Parabolic
Description : Which area is used in case of heat flow by conduction through a cylinder? (A) Logarithmic mean area (B) Arithmetic mean area (C) Geometric mean area (D) None of these
Last Answer : (A) Logarithmic mean area
Description : Heat transfer by __________ is almost absent in case of fluidised bed drying operation. (A) Radiation (B) Conduction (C) Convection (D) Both (B) & (C)
Last Answer : A) Radiation
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 : The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law. (A) Kirchoff’s (B) Planck's (C) Wien's displacement (D) Stefan-Boltzmann
Last Answer : (A) Kirchoff’s
Description : Magnification factor is the ratio of the maximum displacement due to forced vibrations to the deflection due to _______ A Static force B Dynamic force C Torsion D Compression
Last Answer : A Static force
Description : The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as A Damping factor B Damping coefficient C Logarithmic decrement D Magnification factor
Last Answer : D Magnification factor
Description : The ratio of the maximum displacement of the forced vibration to the deflection due to the static force is known as A Logarithmic decrement B Magnification factor C Damping factor D None of the mentioned
Last Answer : B Magnification factor
Description : Transmissibility in a support excitation system is defined by A) Ratio of absolute amplitude of the mass to the excitation amplitude of the support B) Reciprocal of (a) C) Ratio of the ... the foundation, to the equivalent force corresponding to maximum displacement excitation D) None of the above
Last Answer : B) Reciprocal of (a)
Description : In measuring critical speed of shaft experiment, it was found that the frequency ratio is 0.707 when the eccentricity is 0.05 m. what will be the displacement of the system. A. 0.05 m B. 0.005 m C. 0.5 m D. Infinite
Last Answer : A. 0.05 m
Description : The ratio of maximum displacement of the forced vibration to the deflection due to the static force, is known as A. Damping FactorB. Damping Coefficient C. Logarithmic Decrement D. Magnification Factor
Last Answer : D. Magnification Factor
Description : Transmissibility is the ratio of a. force transmitted and exciting force b. force applied and the resulting displacement c. input displacement and output displacement
Last Answer : a. force transmitted and exciting force
Description : The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as a) Damping factor b) Damping coefficient c) Logarithmic decrement d) Magnification factor
Last Answer : d) Magnification factor
Description : The ratio of the maximum displacement of the forced vibration to the deflection due to the static force is known as (A) damping factor (B) damping coefficient (C) logarithmic decrement (D) magnification factor
Last Answer : (D) magnification factor
Description : Magnification factor is the ratio of the maximum displacement due to forced vibrations to the deflection due to _______ a) Static force b) Dynamic force c) Torsion d) Compression
Last Answer : a) Static force
Description : The ratio of the maximum displacement of the forced vibration to the deflection due to the static force, is known as a) damping factor b) damping coefficient c) logarithmic decrement d) magnification factor
Last Answer : d) magnification factor
Description : The ratio of real depth to apparent depth is called : A. Refractive index B. Critical angle C. Lateral displacement D. None
Last Answer : A. Refractive index