Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
Last Answer : Answer: A
Description : In transformer, the core is made up of soft iron in order to pass the maximum A. flux B. current C. magnetic flux D. voltage
Last Answer : magnetic flux
Description : A copper rod which is 1 centimeter in diameter carries a current of 5 amps. The current is distributed uniformly throughout the rod. The magnetic field half way between the axis of the rod and its ... ) zero. x) pointing radially outward y) pointing radially inward z) circles the axis of the rod
Last Answer : ANSWER: Z -- CIRCLES THE AXIS OF THE ROD
Description : An infinitely long wire carries a current of three amps. The magnetic field outside the wire: w) points radially away from the wire x) points radially inward y) circles the wire z) is zero.
Last Answer : ANSWER: Y -- CIRCLES THE WIRE
Description : The Weber and the Maxwell are units of measure of: w) conductance x) electrical current y) magnetic flux z) relative speed
Last Answer : ANSWER: Y -- MAGNETIC FLUX
Description : The Tesla and the Gauss are units of measure of: w) conductance x) magnetic field strength y) magnetic flux z) electrical current
Last Answer : ANSWER: X -- MAGNETIC FIELD STRENGTH
Description : are used for construction of core of electromagnets. (a) Soft magnetic materials (b) Hard magnetic materials (c) Either (a) or (b) (d) None of the above
Last Answer : (a) Soft magnetic materials
Description : Most earthquakes originate at depths of between w) the surface and 100 kilometers x) 100 kilometers and 500 kilometers y) 500 kilometers and 700 kilometers z) 700 kilometers and the outer core
Last Answer : ANSWER: W -- THE SURFACE AND 100 KILOMETERS
Description : If reading the AC voltage from a typical wall outlet, the range switch of the device illustrated should be set to ___________. EL-0047 A. 1,000 V B. 250 V C. R X 10,000 D. 10 ma/amps
Last Answer : Answer: B
Description : For a point charge to feel a net force in a homogeneous magnetic field, which one of the following statements is true? The charge must: w) move parallel to the magnetic lines of flux x) have a component of its motion perpendicular to the lines of flux y) be stationary z) be a positive charge
Last Answer : ANSWER: X -- HAVE A COMPONENT OF ITS MOTION PERPENDICULAR TO THE LINES OF FLUX
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 : If two coils are wound on a single iron core, what will a change in current in one coil cause in the other coil?
Last Answer : A change in inductance.
Description : A small dairy farm daily produces 100 kilograms of average quality buffalo milk and sells it to an organised dairy at the rate of Rs. 100 per kilogram of total solids contained in the milk. How much would be the daily gross ... (D) Between Rs. 1,000 and Rs. 1,100 (E) Between Rs. 1,650 and Rs. 1,850
Last Answer : (B) Between Rs. 1,250 and Rs. 1,400
Description : The greatest induced EMF will occur in a straight wire moving at constant speed through a uniform magnetic field when the angle between the direction of the wire's motion and the direction of the magnetic field is w) 0 degrees x) 30 degrees y) 60 degrees z) 90 degrees
Last Answer : ANSWER: Z -- 90 DEGREES
Description : 27] In a transformer, the leakage flux of each winding is proportional to the current in that winding because A. Ohm's law applies to magnetic circuits B. Leakage paths do no saturate C. the two windings are electrically isolated D. mutual flux is confined to the core
Last Answer : B. Leakage path do not saturate
Description : Which of the following number of years best approximates the length of time since the last ice age in the United States? w) 1,000,000 x) 1,000 y) 11,000 z) 250,000
Last Answer : ANSWER: Y -- 11,000
Description : What is the impedance of a one microfarad capacitor at 60 Hertz: w) 16,700 ohms x) 2,650 ohms y) 3.8x10-4 ohms z) 6x10-5 ohms
Last Answer : ANSWER: X -- 2,650 OHMS
Description : One barrel of oil has about the same heat content as how much coal: w) 70 pounds x) 700 pounds y) 1,400 pounds z) 2,800 pounds
Last Answer : ANSWER: X -- 700 POUNDS
Description : A synchronous motor maintains synchronism with the rotating field because _____________. A. field strength varies directly with rotor slip B. DC current applied to the rotor coils causes the rotor ... the flux created by the excitation current D. the stator flux rotates in the opposite direction
Description : The equivalent inductance of two coils with series opposing flux having inductances 7H and 2H with a mutual inductance of 1H. a) 10 b) 7 c) 11 d) 13
Last Answer : b) 7
Description : Iron is what type of magnetic material? Is it: w) diamagnetic x) paramagnetic y) ferromagnetic z) non-magnetic
Last Answer : ANSWER: Y -- FERROMAGNETIC
Description : The design of electromagnets is based upon which of the following fundamental equations ? (a) Force equation (b) Magnetic circuit equation (c) Heating equation (d) Voltage equation (e) All of the above
Last Answer : (e) All of the above
Description : A load with an impedance of 440 ohms is connected across the secondary of the transformer illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given
Description : A load with an impedance of 440 ohms is connected across the secondary of the device illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given
Description : An electrical discharge ionizing the air around a conductor is called: w) Flux x) Corona y) Ozone z) Field
Last Answer : ANSWER: X -- CORONA
Description : An object with a mass of 5 kilograms is a distance of 5 meters above the surface of the earth. If the acceleration due to gravity is 10 meters per second squared, the potential energy of the object relative to the ... is: w) 10 joules x) 20 joules y) 100 joules z) 250 joules e) none of the above
Last Answer : ANSWER: Z -- 250 JOULES
Description : A machine having an efficiency of 50% does 500 joules of work. Which of the following is the work input? Is it: w) 500 joules x) 250 joules y) 1000 joules z) 2500 joules
Last Answer : ANSWER: Y -- 1000 JOULES
Description : Which of the following metals is used in the electromagnets? (a) Soft iron (b) Stainless steel (c) Cobalt (d) Copper
Last Answer : Ans:(a)
Description : The shape of a magnetic field around a long straight current carrying wire is: w) elliptical. x) square y) varies depending on the magnitude of the current z) circular
Last Answer : ANSWER: Z -- CIRCULAR
Description : Magnetic fields are produced by: w) resistance x) an electric potential difference y) electric current z) stationary charge
Last Answer : ANSWER: Y -- CURRENT
Description : The magnetic field produced by a long straight wire carrying a current points: w) in the direction of the current x) toward the wire y) away from the wire z) circles around the wire
Last Answer : ANSWER: Z -- CIRCLES AROUND THE WIRE
Description : If the magnetic flux density and current are at right angles, then component of force acting on the conductor is A. BIL cosθ B. BIL sinθ C. BIL tanθ D. BL sinθ
Last Answer : BIL sinθ
Description : For a straight wire, induced current depends uponA. the speed of movement of wire B. the length of wire C. the magnitude of magnetic flux density D. all of above
Last Answer : all of above
Description : Magnitude of induced e.m.f is proportional to A. rate of change of current B. rate of change of voltage C. rate of change of magnetic flux linkage D. rate of change of resistance
Last Answer : rate of change of magnetic flux linkage
Description : Hall voltage is directly proportional to A. current B. electric field C. magnetic flux density D. all of above
Last Answer : magnetic flux density
Description : An electron is travelling at right angles to a uniform magnetic field of flux density 1.2 mT with a speed of 8 × 106 m s-1, the radius of circular path followed by electron is A. 3.8 cm B. 3.7 cm C. 3.6 cm D. 3.5 cm
Last Answer : 3.8 cm
Description : The core of the earth is thought to be composed of which of the following? w) basalt and granite x) compressed gases y) uranium and lead z) iron and nickel
Last Answer : ANSWER: Z -- IRON AND NICKEL
Description : Why not reduce the noise in the core by reducing the amount of flux?
Last Answer : Transformer voltages are fixed by system requirements. The ratio of these voltages to the number of turns in the winding determines the amount of magnetization. This ratio of voltage to turns is determined ... flux at the normal voltage is fixed. This also fixes the level of noise and vibration.
Description : [53] The iron loss of the transformer is negligible during short circuit test because A. The entire input is just sufficient to meet Cu losses only B. Flux produced is a small fraction of the normal flux C. Iron core becomes fully saturated D. Supply frequency is held constant
Last Answer : B. Flux produced is a small fraction of the normal flux
Description : Which of the following are the parts of a DC generator that convert the AC in the armature to DC in the external circuit. Are these parts the: w) field poles x) slip rings and the brushes y) commutator and the brushes z) armature and the core
Last Answer : ANSWER: Y -- COMMUTATOR AND THE BRUSHES
Description : When the series field relay "FR" of the winch circuit shown in the illustration is energized during dynamic braking the _______________. EL-0102 A. shunt Field Relay "FR-B.O." is de-energized and contacts ... . shunt Field Relay "FR-B.O." opposes the series coil's flux and sets the mechanical brake
Description : The flux lines of two energised coils overlapping on each other will give a) Series aiding b) Shunt aiding c) Series opposing d) Shunt opposing
Last Answer : a) Series aiding
Description : The equivalent inductances of two coils 2H and 5H in series aiding flux with mutual inductance of 3H is a) 10 b) 30 c) 1 d) 13
Last Answer : d) 13
Description : A 8-pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at 250 rpm. The induced armature voltage is (A) 96 V (B) 192 V (C) 384 V (D) 768 V
Last Answer : A 8-pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at 250 rpm. The induced armature voltage is 384 V
Description : A direct current passing through a wire coiled around a soft iron core is the description of a simple ____________. A. magnetic shield B. electromagnet C. piezoelectric device D. electromagnetic domain
Description : 43 The purpose of providing an iron core in a transformer is to A.Provide support to windings B. Reduce hysteresis loss C. decrease the reluctance of the magnetic path D. reduce eddy current losses
Last Answer : C. Decrease the reluctance of the magnetic path
Description : Find the magnetic flux density of a finite length conductor of radius 12cm and current 3A in air( in 10 -6 order) a) 4 b) 5 c) 6 d) 7
Last Answer : b) 5
Description : The non-relativistic mass of an object w) must be the same as its weight x) depends on where you measure it y) does not change with increasing velocity z) is greatest at the poles
Last Answer : ANSWER: Y -- DOES NOT CHANGE WITH INCREASING VELOCITY
Description : Which of the following quantities has the GREATEST influence on the overall efficiency of a conventional (Rankine cycle) electric generating station burning fossil fuels? w) steam temperature at the steam turbine ... pressure at the steam turbine inlet z) pounds of ash and sulfur per pound of fuel
Last Answer : ANSWER: W -- STEAM TEMPERATURE AT THE STEAM TURBINE INLET
Description : Which of the following implies the greatest precision? w) 1.02 x 105 x) 102 x 103 y) 0.102 x 106 z) 1.020 x 105
Last Answer : ANSWER: Z -- 1.020 x 105