Description : Materials, which provide a path to the magnetic flux, are classified as (A) insulating materials. (B) semi conducting materials. (C) magnetic materials. (D) dielectric materials.
Last Answer : (C) magnetic materials.
Description : Dielectric materials are (A) Insulating materials. (B) Semiconducting materials. (C) Magnetic materials. (D) Ferroelectric materials.
Last Answer : (A) Insulating materials.
Description : Gold and silver are (A) dielectric materials (B) low resistivity conducting materials. (C) magnetic materials. (D) insulating materials.
Last Answer : (B) low resistivity conducting 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 : Give four examples of natural insulating materials.
Last Answer : Ans: Examples of the natural insulating materials are cotton, rubber, wood, mica.
Description : Micanite is a form of (A) Built up mica. (B) Hydrated potassium aluminium silicate. (C) Magnesium mica. (D) Calcium mica.
Last Answer : (A) Built up mica.
Description : The dielectric strength of transformer oil should be (A) 100 V. (B) 5 KV. (C) 30 KV. (D) 132 KV.
Last Answer : (C) 30 KV.
Description : Dielectric constant of vacuum is (A) infinity. (B) 100. (C) one. (D) zero.
Last Answer : (C) one.
Description : The dielectric constant of air is practically taken as (A) more than unity. (B) unity. (C) less than unity. (D) zero.
Last Answer : (B) unity.
Description : Hysteresis loss least depends on (A) Frequency. (B) Magnetic field intensity. (C) Volume of the material. (D) Grain orientation of material.
Last Answer : (D) Grain orientation of material.
Description : In a ferromagnetic material the state of flux density is as follows when external magnetic field is applied to it. (A) Increased (B) Decreased (C) Remains unchanged (D) Becomes zero
Last Answer : (C) Remains unchanged
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 : 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 : Hard magnetic materials are used for making (A) Permanent magnets. (B) Temporary magnets. (C) Conductors. (D) Insulator.
Last Answer : (A) Permanent magnets.
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 : The critical temperature above which the ferromagnetic materials loose their magnetic property is known as (A) hysterisis. (B) Curie point. (C) transition temperature. (D) standard temperature.
Last Answer : (B) Curie point
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 : Tick off the material, which is different from the group (A) Constantan. (B) Manganin. (C) Nichrome. (D) Brass.
Last Answer : (D) Brass.
Description : Example of high resistivity material is (A) Nichrome (B) Silver (C) Gold (D) Copper
Last Answer : (A) Nichrome
Description : Which of the following material has the highest melting point (A) Copper. (B) Aluminium. (C) Tungsten. (D) Gold.
Last Answer : (C) Tungsten.
Description : The most malleable, ductile low resistivity material is (A) Copper. (B) Aluminium. (C) Silver. (D) Iron.
Last Answer : (C) Silver.
Description : Ferrites are (A) ferromagnetic material. (B) ferrimagnetic materials. (C) anti ferromagnetic material. (D) diamagnetic materials.
Last Answer : (A) ferromagnetic material.
Description : The material with lowest resistivity is (A) constantan. (B) silver. (C) manganin. (D) nichrome.
Last Answer : (B) silver.
Description : Property of material which allows it to be drawn out into wires is (A) Ductility. (B) Solder ability. (C) Super conductivity. (D) Malleability.
Last Answer : (A) Ductility.
Description : The insulating material used between the commutator segments is normally (a) graphite (b) paper (c) mica (d) insulating varnish
Last Answer : Ans: c
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 : Dielectric (A) Is an electrical insulating material (B) Of low resistivity is preferred (C) Should have high thermal conductivity (D) Need not defy the corrosive action of chemicals
Last Answer : (A) Is an electrical insulating material
Description : The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above
Last Answer : (d) all of the above
Description : The insulating material for a cable should have (a) low cost (b) high dielectric strength (c) high mechanical strength (d) all of the above
Description : Define dielectric failure of electrical insulating material.
Last Answer : Definition of dielectric failure of electrical insulating material. In the insulating material if the applied voltage is increased gradually then for certain value insulation will break down, ... material vanishes its insulating properties and starts conducting, also known as dielectric failure.
Description : State failure phenomena observed in insulating material. State four reasons for failure of gaseous and solid dielectric materials.
Last Answer : Failure phenomena in insulating material means the dielectric property fails : The dielectric failure mean the dielectric strength of insulating material reduces due to high voltages or high ... 6. Due to poor maintenance of insulating material there may be possibility dielectric failure
Description : What is dielectric strength of an insulating material? What is its unit?
Last Answer : Dielectric Strength: The dielectric strength of an insulating material is the maximum voltage which the insulating medium can withstand without breakdown. Unit is volts per millimeter (V/mm), or kV/mm or kV/cm
Description : For an insulating material, dielectric strength and dielectric loss should be respectively (A) high and high (B) low and high (C) high and low (D) low and low.
Last Answer : For an insulating material, dielectric strength and dielectric loss should be respectively high and low
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 following is not a dielectric material? (A) Cotton, silk and paper (B) Asbestos, glass, porcelain and mica (C) Rubber and polymeric resins (D) All refractory materials
Last Answer : Option C
Description : Write one application for the give dielectric material. (i) Polyvinyl Carbide(PVC) (ii) Glass (iii) Mica (iv) Cotton and Silk
Last Answer : (i) Polyvinyl Carbide(PVC):it is used in insulation of wires and cables in domestic wiring as well as in aircraft and factory wiring (any one) (ii) Glass: 1) Alkaline glasses are used for ... with wax or varnishes are used in windings of magnet coils and small medium sized mechanics (any one)
Description : Fire refining process is employed in case of (A) Tin (B) Copper (C) Zinc (D) Aluminium
Last Answer : (B) Copper
Description : The following type of bonding is strongly directional in solids. (A) Vander Waal's (B) Ionic (C) Metallic (D) Covalent
Last Answer : D) Covalent
Description : What is a modular system? List the important properties of a modular system.
Last Answer : Ans: A modular system consists of well defined manageable units to well defined interfaces among them. Desirable properties are Each module is a well defined subsystem useful to others Each module ... modules Modules should be easier to use than build Modules should have a simple interface
Description : State the functions of a fuse. Mention the desirable properties of fuse materials.
Last Answer : Ans: Fuse is a protective device, which consists of a thin wire or strip. This wire or strip is placed with the circuit it has to protect, so that the circuit-current flows through it. When ... silver and silver alloys are used of lower ratings. Copper alloys are used in fuses of higher ratings.
Description : Classify plastic materials into two categories, describe their important properties and give two examples of each.
Last Answer : Ans: Plastic materials can be classified into thermoplastic and thermosetting plastics. Thermoplastic materials:- The properties of these plastic materials do not change considerably if they are melted ... forming elastic threads and films. Examples are Phenol formaldehyde (Bakelite), Epoxy resins.
Description : Ferroelectric materials are characterised by (A) Very high degree of polarisation. (B) A sharp dependence of polarisation on temperature. (C) Non-linear dependence of the charge Q on the applied voltage. (D) All the above.
Last Answer : (D) All the above.
Description : Tick of the property, which is different from the group (A) Ductility. (B) Resistivity. (C) Tensile strength. (D) Hardness.
Last Answer : (B) Resistivity
Description : Atoms with four valence electrons are good conductors. (A) True (B) False
Last Answer : (B) False
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 : Paper is hygroscopic and absorbent. (A) True (B) False
Last Answer : (A) True
Description : Addition of trivalent impurity to a semiconductor creates many (A) holes. (B) free electrons. (C) valance electrons. (D) bound electrons.
Last Answer : (B) free electrons.
Description : Hall effect is associated with (A) Conductors. (B) Semiconductors. (C) Thermistors. (D) Solders.
Last Answer : (B) Semiconductors.
Description : A transistor has (A) One p-n junction. (B) Two p-n junction. (C) Four p-n junction. (D) Five p-n junction.
Last Answer : (B) Two p-n junction.
Description : Bronze is an alloy of (A) Copper and Tin. (B) Copper and Steel. (C) Copper and Mercury. (D) Copper and Aluminium.
Last Answer : (A) Copper and Tin.