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 : Electrons which are free to move around are also called A. conduction electrons B. valence shell electrons C. inner electrons D. electron sea
Last Answer : conduction electrons
Description : Find the range of band gap energy for conductors. a) >6 eV b) 0.2-0.4 eV c) 0.4-2 eV d) 2-6 eV
Last Answer : b) 0.2-0.4 eV
Description : Conduction in metals is due to a) Electrons only b) Electrons and holes c) Holes only d) Applied electric field
Last Answer : a) Electrons only
Description : In a conductor – (1) there is no conduction band (2) the forbidden energy gap is very wide (3) the forbidden energy gap is very narrow (4) the valence band and the conduction band overlap each other
Last Answer : (4) the valence band and the conduction band overlap each other Explanation: In the case of a conductor, there is no forbidden energy gap. The conduction and valence energy bands overlap ... , the electrons from the valence band can freely enter the conduction energy band. Conduction energy band
Description : Insulators have (A) A full valence band. (B) An empty conduction band. (C) A large energy gap. (D) All the above.
Last Answer : (C) A large energy gap.
Description : In a conductor (1) there is no conduction band (2) the forbidden energy gap is very wide (3) the forbidden energy gap is very narrow (4) the valence band and the conduction band overlap each other
Last Answer : the valence band and the conduction band overlap each other
Description : How many valence electrons do conductors such as copper have?
Last Answer : Good conductors have one to three valence electrons. Copperitself has one valence electron.
Description : Atoms with four valence electrons are good conductors. (A) True (B) False
Last Answer : (B) False
Description : The skin effect is a phenomenon observed in a) Insulators b) Dielectrics c) Conductors d) Semiconductors
Last Answer : c) Conductors
Description : In conductors, the E and H vary by a phase difference of a) 0 b) 30 c) 45 d) 60
Last Answer : c) 45
Description : For conductors, the loss tangent will be a) Zero b) Unity c) Maximum d) Minimum
Last Answer : c) Maximum
Description : In perfect conductors, the phase shift between the electric field and magnetic field will be a) 0 b) 30 c) 45 d) 90
Description : In conductors, which two parameters are same? a) Wavelength and phase constant b) Phase and attenuation constant c) Attenuation constant and skin depth d) Skin depth and wavelength
Last Answer : b) Phase and attenuation constant
Description : In conductors, which condition will be true? a) σ/ωε > 1 b) σωε > 1 c) σ/ωε < 1 d) σωε < 1
Last Answer : a) σ/ωε > 1
Description : Skin depth phenomenon is found in which materials? a) Insulators b) Dielectrics c) Conductors d) Semiconductors
Description : An implication of the continuity equation of conductors is given by a) J = σ E b) J = E/σ c) J = σ/E d) J = jwEσ
Last Answer : a) J = σ E
Description : When currents are moving in the same direction in two conductors, then the force will be a) Attractive b) Repulsive c) Retracting\ d) Opposing
Last Answer : a) Attractive
Description : The force per unit length of two conductors carrying equal currents of 5A separated by a distance of 20cm in air(in 10 -6 order) a) 25 b) 35 c) 40 d) 50
Last Answer : a) 25
Description : In good conductors, the electric and magnetic fields will be a) 45 in phase b) 45 out of phase c) 90 in phase d) 90 out of phase
Last Answer : b) 45 out of phase
Description : Which of the following are conductors? a) Ceramics b) Plastics c) Mercury d) Rubber
Last Answer : c) Mercury
Description : Dielectric constant will be high in a) Conductors b) Semiconductors c) Insulators d) Superconductors
Last Answer : c) Insulators
Description : What happens to the electrons of a gallium-arsenide semiconductor when they move from the normal low-energy conduction band to the high-energy conduction band?
Last Answer : The electrons become immobile.
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 : Conduction band electrons have more mobility than holes because they (1) are lighter (2) experience collision less frequently (3) have negative charge (4) need less energy to move them
Last Answer : experience collision less frequently
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 : Calculate the conduction current density when the resistivity of a material with an electric field of 5 units is 4.5 units. a) 22.5 b) 4.5/5 c) 5/4.5 d) 9.5
Last Answer : c) 5/4.5
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 magnitude of the conduction current density for a magnetic field intensity of a vector yi + zj + xk will be a) 1.414 b) 1.732 c) -1.414 d) -1.732
Last Answer : b) 1.732
Description : Calculate the conduction density of a material with resistivity of 0.02 units and electric intensity of 12 units. a) 300 b) 600 c) 50 d) 120
Last Answer : b) 600
Description : Find the conduction current density of a material with conductivity 200units and electric field 1.5 units. a) 150 b) 30 c) 400/3 d) 300
Last Answer : d) 300
Description : A boundary of separation between two magnetic materials is identified by which factor? a) Change in the permeability b) Change in permittivity c) Change in magnetization d) Conduction
Last Answer : a) Change in the permeability
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 : Calculate the electric field when the conductivity is 20 units, electron density is 2.4 units and the velocity is 10m/s. Assume the conduction and convection current densities are same. a) 2.4 b) 4.8 c) 3.6 d) 1.2
Last Answer : d) 1.2
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
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 : Find the conductivity of a material with conduction current density 100 units and electric field of 4 units. a) 25 b) 400 c) 0.04 d) 1600
Description : Find the conduction current density when conductivity of a material is 500 units and corresponding electric field is 2 units. a) 500 b) 250 c) 1000 d) 2000
Last Answer : c) 1000
Description : The current flowing through an insulating medium is called a) Conduction b) Convection c) Radiation d) Susceptibility
Last Answer : b) Convection
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 : Insulators perform which of the following functions? a) Conduction b) Convection c) Provide electrical insulation d) Allows current leakage at interfaces
Last Answer : c) Provide electrical insulation
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 : (2) experience collision less frequently Explanation: When an electric field is applied, both the valence electrons and the free electrons move in the same direction. The hole direction is opposite to that ... to free electrons. This means mobility is also less for a hole compared to free electron.
Last Answer : Carbon dioxide is called a greenhouse gas because - (1) its concentration remains always higher than other gases (2) it is used in photosynthesis (3) it absorbs infrared radiation (4) it emits visible radiation
Description : Which components exist in an electromagnetic wave? a) Only E b) Only H c) Both E and H d) Neither E or H
Last Answer : c) Both E and H
Description : Which of the following is true regarding magnetic lines of force? a) Real b) Imaginary c) Does not exist d) Parallel to field
Last Answer : b) Imaginary
Description : The potential difference in an open circuit is a) Zero b) Unity c) Infinity d) Circuit does not exist open
Last Answer : c) Infinity
Description : If two functions A and B are discrete, their Green’s value for a region of circle of radius a in the positive quadrant is a) ∞ b) -∞ c) 0 d) Does not exist
Last Answer : d) Does not exist
Description : Choose which of following condition is not required for a waveguide to exist. a) The dimensions should be in accordance with desired frequency b) Cut-off frequency should be minimum 6GHz c) The shape should be spherical d) No specific condition is required for waveguide design
Last Answer : c) The shape should be spherical