Last Answer : Materials subjected to rapid reversal of magnetism should have high permeability and low hysteresis loss.
Description : The energy required to magnetize and demagnetize is called a) Saturation b) Retentivity c) Coercivity d) Hysteresis loss
Last Answer : d) Hysteresis loss
Description : Materials that retain a large part of their magnetization, after the magnetizing force is removed, are said to have _____________. A. low hysteresis loss B. high flux density C. high permanence D. high permeability
Last Answer : Answer: C
Description : The materials having low retentivity are suitable for making (a) weak magnets (b) temporary magnets (c) permanent magnets (d) none of the above
Last Answer : (b) temporary magnets
Description : Pick out the wrong statement. (A) A soft magnetic material should have high permeability and small area of hysteresis loop (B) Poisson's ratio of high melting point metals is more than unity (C) ... less than 185°C (D) Steel produced by B.O.F process is ideally suited for manufacturing flat product
Last Answer : Option B
Description : If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be?
Last Answer : If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be large.
Description : Straight silicon steel (containing Si from 0.5 to 5%) because of their low hysteresis loss and high magnetic permeability are used for electrical appliances. Which of the following electrical ... /generators (B) Generators and small motors (C) Induction motors (D) High frequency transformers
Last Answer : (D) High frequency transformers
Description : A ferrite core has less eddy current loss than an iron core because ferrites have (A) High resistance. (B) Low resistance. (C) Low permeability. (D) High hysteresis.
Last Answer : (A) High resistance.
Description : Which of the following properties is not necessarily desirable in the material for transformer core? A. Mechanical strength B. Low hysteresis loss C. High thermal conductivity D. High permeability
Last Answer : C) high thermal conductivity
Description : The loss of energy over each A.C cycle magnetization and demagnetization of transformer, is called: a. Magnetization loss b. Hysteresis loss c. Demagnetization loss d. energy loss
Last Answer : c. Demagnetization loss
Description : A transformer: a. Works on A.C. only b. Works on D.C only c. Works on A.C. and D.C d. Has no hysteresis loss
Last Answer : a. Works on A.C. only
Description : Paramagnetic materials have relative permeability (a) slightly less than unity (b) equal to unity (c) slightly more than unity (d) equal to that ferromagnetic mate rials
Last Answer : (c) slightly more than unity
Description : An elastic behaviour of materials is expressed in terms of (A) Hysteresis loop area (B) Stress-strain curve (C) Relaxation time
Last Answer : (C) Relaxation time
Description : Please ripley me due to emergency
Last Answer : To calculate the flux density in the ring, you need to use the following formula: B = (μ * I * N) / (2 * π * r) where: B is the flux density in the ring (in teslas) μ is the relative permeability ... 2 * π * 0.127 m) = 0.53 T So the flux density in the ring would be approximately 0.53 teslas.
Description : The ratio of intensity of magnetisation to the magnetisation force is known as (a) flux density (b) susceptibility (c) relative permeability (d) none of the above
Last Answer : (b) susceptibility
Description : Which of the following is a vector quantity ? (a) Relative permeability (b) Magnetic field intensity (c) Flux density (d) Magnetic potential
Last Answer : (b) Magnetic field intensity
Description : Magnetising steel is normals difficult because (a) it corrodes easily (6) it has high permeability (c) it has high specific gravity (d) it has low permeability
Last Answer : (d) it has low permeability
Last Answer : The materials having low retentivity are suitable for making temporary magnets.
Description : 71 High frequency transformers sometimes make use of ferrite cores because it has A. High specific gravity B. High resistance C. High hysteresis D. low permeability
Last Answer : B. High resistance
Description : Draw B-H curve for magnetic material and state its nature. State the significance of hysteresis loop. Also draw the hysteresis loop for hard steel and soft steel.
Last Answer : B-H curve for magnetic material: The B-H curve is the graphical representation of relation between flux density (B) and applied field strength (H), with H plotted on the x-axis and B plotted on ... or crossing an air gap tends to bulge outwards the iron ring, this effect is called as Fringing .
Description : Indicate which of the following material does not retain magnetism permanently. (a) Soft iron (b) Stainless steel (e) Hardened steel (d) None of the above
Last Answer : (a) Soft iron
Description : What is residual magnetism?*
Last Answer : Magnetism remaining in a Ferro magnetic material after the removal of magnetizing force.
Description : What is residual magnetism? Where is it important?
Last Answer : Residual magnetism is a property in which certain amount of excitation remains back in the conductor even after the removal of the magnets. It is required as we need some magnetism to start off the generation before the field winding has power to produce the full field.
Description : What is the meaning of residual magnetism?
Last Answer : Residual magnetism is a property in which certain amount of excitation remains back in the conductor even after the removal of the magnets.
Description : A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop: a. depends on the shape b. depends on area c. depends on nature of loop d. zero
Last Answer : d. zero
Description : Those materials are well suited for making permanent magnets which have _____ retentivity and _______ coercivity.
Last Answer : Those materials are well suited for making permanent magnets which have high retentivity and high coercivity.
Description : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : (A) 256 W (B) 320 W (C) 500 W (D) 625 W
Last Answer : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : 625 W
Description : Substances which have permeability less than the permeability of free space are known as (a) ferromagnetic (b) paramagnetic (c) diamagnetic (d) bipolar
Last Answer : (c) diamagnetic
Description : The unit of relative permeability is (a) henry/metre (b) henry (c) henry/sq. m (d) it is dimensionless
Last Answer : (d) it is dimensionless
Description : Pick out the wrong statement. (A) A ferromagnetic material becomes paramagnetic above the 'Curie temperature' (B) Permanent magnets are made of hard materials, whereas electromagnets require soft ... hysterisis loss and coercive forces (D) Tungsten steel and alnico are not hard magnetic materials
Last Answer : Option D
Description : State Magneto-striction. Draw Hysteresis loop for : (i) High silicon steel (ii) Copper (iii) Soft iron (iv) Wood
Last Answer : Magneto-striction: It is the change in dimensions of ferro magnetic material when it is magnetized for eg. Silicon steel, iron or any ferromagnetic material. i) Hysteresis loop for High silicon steel : ... loop for Soft iron : iv) Hysteresis loop for Copper and Wood :
Description : Anantenna thatis currentlypolarized usthe a. helical b. small circular loop c. parabolic reflector d. Yagi-Uda
Last Answer : a. helical
Description : One ofthe followingis veryuseful as amultibandHFreceivingantenna.Thisisthe: a. conical horn b. folded dipole c. log periodic d. square loop
Last Answer : c. log periodic
Description : The open loop gain of the amplifier is ______ (a) 105 (b) 103 (c) 106 (d) 108
Last Answer : (a) 105
Description : The induced current can be increased by: a. Using strong magnetic field b. moving loop faster c. Replacing loop by coil d. all of above
Last Answer : d. all of above
Description : One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents
Last Answer : Answer: D
Description : Draw Hysteresis loop for Hard steel and soft steel. Also write one application of each material.
Last Answer : Application of Hard steel: Fig. (a) Shows hysteresis loop for hard steel. Such materials are used for producing permanent magnets. Such a hysteresis loop represents a large residual ... Residual flux & coercive force are less. Hence material can be used for making the electromagnets.
Description : Explain the hysteresis loop of a magnetic material with neat diagram.
Last Answer : Hysteresis loop of magnetic material: The circuit arrangement for plotting the hysteresis loop is shown in figure given below. The electromagnetic part consists of a coil wound on the iron ring ... one magnetic reversal is called hysteresis loop. Meaning of hysteresis is to lag behind.
Last Answer : It is B-H curve of magnetic material, it shows retetivity,coercivity & other propert of magnetic matetial like Iron It helps in choosing the material for designing of rotor poles
Description : Which of the following reactions occuring during coal gasification is called the Neumann reversal reaction? (A) 2CO ↔ C + CO2 (B) CO + H2O ↔ CO2 + H2 (C) C + H2O ↔ CO + H2 (D) C + 2H2O ↔ CO2 + 2H2
Last Answer : (A) 2CO ↔ C + CO2
Description : Ferrites are materials. (a) paramagnetic (b) diamagnetic (c) ferromagnetic (d) none of the above
Last Answer : (c) ferromagnetic
Description : Whichofthe followingterms describesthe reason thatlightisrefractedat different angles? a. Photon energy changes with wavelength b. Light is refracted as a function of surface smoothness c. The angle is determined partly by a and b d. The angle is determined by the index of the materials
Last Answer : d. The angle is determined by the index of the materials
Description : Which one of the following materials is useful for making bulb filaments? a. aluminum b. Iron c. Copper d. Tungsten
Last Answer : a. aluminum
Description : Classify electrical materials.
Last Answer : Classification of electrical materials: i) Conducting Materials ii) Insulating materials iii) Magnetic materials iv) Semiconducting materials
Description : The speed of hydrogen electron in the nth orbit is given by vn = a) 2λke2 / nh b) 2πke2 / λh c) 2πke2 / nh d) 2πke2 / h
Last Answer : c) 2πke2
Description : For Hydrogen atom, the allowed stationary orbits are those whose orbital angular momentum is equal to an integral multiple of h i.e., mvr = a) nh/2π b) nh x 2π c) nh / 2λ d) nh / 2πλ
Last Answer : a) nh/2π
Description : Certain characteristic demographic features of developing countries are (a) high fertility, low or rapidly falling mortality rate, rapid population growth and a very young age distribution (b) high ... (d) high mortality, high density, uneven population growth and a very old age distribution.
Last Answer : (a) high fertility, low or rapidly falling mortality rate, rapid population growth and a very young age distribution
Description : Tesla is a unit of (a) field strength (b) inductance (c) flux density (d) flux
Last Answer : (c) flux density
Description : CAT Scanners can detect density differences of the order of a) 50 percent b) 10 percent c) 1 percent d) 40 percent
Last Answer : c) 1 percent
Description : Energy stored per unit volume inside the solenoid is called: a. Energy density b. Charge Density c. Mass density d. Volume charge density
Last Answer : energy density is correct