A. 20 Wb
B. 2 Wb
C. 0.2 Wb
D. 0.02 Wb

A. 5 mH
B. 10 mH
C. 5 H
D. 10 H

A. unaffected
B. doubled
C. halved

## As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it_______________?

A. lies perpendicular to the magnetic flux
B. lies in a magnetic field
C. cuts magnetic flux
D. moves parallel to the direction of the magnetic field

A. 64 A/s
B. 32 A/s
C. 16 A/s
D. 4 A/s

## An open coil has_____________?

A. zero resistance and inductance
B. infinite resistance and zero inductance
C. infinite resistance and normal inductance
D. zero resistance and high inductance

B. Lenz
C. Newton
D. Coulomb

## The magnitude of the induced e.m.f. in a conductor depends on the______________?

A. flux density of the magnetic field
B. amount of flux cut
D. rate of change of flux-linkages

## An ammeter should have_____________ resistance?

A. Infinite
B. Very large
C. Very low
D. None of the above

## An ammeter is connected in __________ with the circuit element whose current we wish to measure?

A. Series
B. Parallel
C. Series or parallel
D. None of the above

A. nG
B. (n-1)G
C. G/(n-1)
D. G/n

## A galvanometer in series with a high resistance is called_______________?

A. An ammeter
B. A voltmeter
C. A wattmeter
D. None of the above

## A galvanometer of resistance G is shunted by a very small resistance S. The resistance of the resulting ammeter is ______________?

A. GS/(G+S)
B. G+S
C. G-S
D. None of the above

A. Low
B. Infinite
C. Zero
D. High

A. 3 kO
B. kO
C. kO
D. 6 kO

## A VTVM is never used to measure ______________?

A. Voltage
B. Current
C. Resistance
D. None of the above

## A VTVM has_____________input resistance than that of a multi meter?

A. More
B. Less
C. Same
D. None of the above

## A voltmeter should have ____________resistance?

A. Zero
B. Very high
C. Very low
D. None of the above

A. nG
B. G/n
C. G/(n-1)
D. (n-1)G

## A voltmeter is connected in a _____________ with the circuit component across which potential difference is to be measured?

A. Parallel
B. Series
C. Series or parallel
D. None of the above

A. Voltage
B. Frequency
C. Phase
D. All of above

## Which of the fpllowing inductor will have the least eddy current losses ?

A. Air core
B. Laminated iron core
C. Iron core
D. Powdered iron core

A. 300 uH
B. 600 uH
C. 150 uH
D. 75 uH

A. 4 mH
B. 5 mH
C. 6 mH
D. 12 mH

A. Yes
B. No

A. Yes
B. No

## The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as__________?

A. self-inductance
B. mutual inductance
C. series aiding inductance
D. capacitance

A. 32 mH
B. 38 mH
C. 40 mH
D. 48 mH

A. 6 H
B. 8 H
C. 12 H
D. 24 H

A. Ohm
B. Henry
C. Ampere turns
D. Webers/metre

## Which of the following is not a unit of inductance ?

A. Henry
B. Coulomb/volt ampere
C. Volt second per ampere
D. All of the above

## Which of the following circuit elements will oppose the change in circuit current ?

A. Capacitance
B. Inductance
C. Resistance
D. All of the above

## Which circuit element(s) will oppose the change in circuit current ?

A. Resistance only
B. Inductance only
C. Capacitance only
D. Inductance and capacitance

## Which of the following circuit element stores energy in the electromagnetic field ?

A. Inductance
B. Condenser
C. Variable resistor
D. Resistance

## Batteries are charged by_____________?

A. rectifiers
B. engine generator sets
C. motor generator sets
D. any one of the above methods

A. 0.1V
B. 0.26 V
C. 1.1 V
D. 2 V

## In D.C. machines the usual limit of slot pitch is________________?

A. between 5 to 10 mm
B. between 10 to 15 mm
C. between 15 to 20 mm
D. between 25 to 35 mm

## In D.C. machines the number of slots per pole usually lies___________?

A. between 2 to 4
B. between 6 to 8
C. between 9 to 16
D. between 20 to 30

## In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?

A. increase
B. decrease
C. either of the above
D. none of the above

A. 10 m/s
B. 20 m/s
C. 30 m/s
D. 40 m/s

## In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?

A. equal to that of armature mmf
B. less in comparison with the armature mmf
C. large in comparison with the armature mmf
D. none of the above

A. 4 mm
B. 6 mm
C. 8 mm
D. 10 mm

## In direct cooled system using hydrogen both stator and rotor conductors are made____________?

A. solid
B. hollow
C. perforated
D. any ofthe above

## Machines cooled by direct cooling method may be called_____________?

A. “supercharged”
B. “inner cooled”
C. “conductor cooled”
D. any of the above

A. Mild steel
B. Copper
C. Aluminium
D. Cast-iron

## In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?

A. 5 percent
B. 10 percent
C. 15 percent
D. 30 percent
E. none of the above

## In induction motors, the length of air gap in kept as small as mechanically possible is order to have____________?

A. low power factor
B. high power factor
D. any of the above

## In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?

A. 2 to 3 times greater
B. 3 to 4 times greater
C. 4 to 5 times greater
D. none of the above

## In a D.C. machine the number of brush arms is _________ the number of poles?

A. less than
B. equal to
C. greater than
D. none of the above

A. 100 A
B. 200 A
E. 300 A
D. 400 A

## For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?

A. 1.0 Wb/m2
B. 1.1 Wb/m2
C. 1.3 Wb/m2
D. 1.6 Wb/m2
E. None of the above

## electromagnets generally function as holding magnets ?

A. Tractive
B. Portative
C. Either of the above
D. None of the above

## Electrical machines having power outputs ranging from a few kW up to approximately 250 kW may be classified as_____________?

A. small size machines
B. medium size machines
C. large size machines
D. any of the above

## Dummy coil should not be used in_________________?

A. small machines
B. large machines
C. either A. or B.
D. none of the above

## Electrical machines having a power output up to about 750 W may be called__________machines?

A. small size
B. medium size
C. large size
D. any of the above

## For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?

A. 1.0 to 1.2 A/mm2
B. 1.5 to 2.0 A/mm2
C. 2.2 to 3.2 A/mm2
D. 3.2 to 4.2 A/mm2

## Helical windings are used in________________?

A. distribution transformers
B. power transformers
C. shell type transformers
D. none of the above

## In _________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?

A. small
B. medium
C. large
D. any of the above.

## impose limitation on design____________?

A. Saturation
B. Temperature rise
C. Efficiency
D. Power factor
E. All above

## If an insulating material is operated beyond the maximum allowable temperature, its life is_____________?

A. drastically increased
B. drastically reduced
C. unaffected
D. none of the above

## Hot rolled sheets have ___________ value of permeability?

A. zero
B. low
C. high
D. none of the above

A. 1.5
B. 2.5
C. 3.5
D. 4.5

## Materials exhibiting zero value of resistivity are known as ____________ ?

A. conductors
B. semiconductors
C. insulators
D. superconductors

## Multi-layer helical windings are commonly used in the transformers as high voltage windings_______________?

A. upto 20 kV
B. upto 50 kV
C. upto 80 kV
D. for 110 kV and above

## The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?

A. Conduction
B. Convection
D. All of the above

## The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

A. Corrugations
B. Fins
C. Tubes
E. All of the above

## The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc?

A. conduction
B. convection
D. any of the above

A. 40°C
B. 60°C
C. 80°C
D. 104°C

## The forced oil and air circulation method is usual one for transformers of capacities____________?

A. upto 5 MVA
B. upto 10 MVA
C. upto 20 MVA
D. 30 MVA upwards

## The high voltage winding is usually which of the following type ?

A. Cylindrical winding with circular conductors
B. Cross-over winding with either circular or small rectangular conductors
C. Continuous disc type winding with rectangular conductors
D. All of the above types

## The input impedance of a JFET is _____________that of an ordinary transistor?

A. equal to
B. less than
C. more than
D. none of the above

## The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?

A. air
B. hydrogen
C. either A. or B.
D. none of the above

## The mcrease in heat dissipation by air blasts is due to increase in______________?

A. conduction
B. convection
D. any ofthe above

## The length cf air gap to be provided in __________ is primarily determined by power factor consideration?

A. d.c. series motor .
B. d.c. shunt motor
C. induction motor
D. synchronous motor

## The insulation between windings and grounded core and the insulation between the windings of the same phase is called__________________?

A. minor insulation
B. major insulation
C. either of the above
D. none of the above

A. 0.1 to 0.2 mm
B. 0.2 to 0.3 mm
C. 0.3 to 0.4 mm
D. 0.4 to 0.5 mm

## The efficiency of a machine should be as ____________ as possible to reduce the operating cost?

A. high
B. low
C. either of the above
D. none of the above

## The distance between the starts of two consecutive coils measured in terms of coil sides is called_____________?

A. front pitch
B. winding pitch
C. commutator pitch
D. back pitch

## The action of electromagnetic machines can be related to which of the following basic principles __________?

A. Induction
B. Interaction
C. Alignment
D. All of the above

## Power transformers should be designed to have maximum efficiency________________?

C. at or near full load
D. any of the above

## Power transformers have rating_______________?

A. equal to 50 kVA
B. equal to 100 kVA
C. above 200 kVA
D. none of the above

A. 10 MW
B. 30 MW
C. 60 MW
D. 150 MW

## On which of the following variables heat convected depends ?

A. Power density
B. Temperature difference between heated surface and coolant
C. Thermal resistivity, density, specific heat
D. Gravitational constant
E. All of the above

## The change in flux linkages can be caused in which of the following ways ?

A. The flux is constant with respect to time and is stationary and the coil moves through it
B. The coil is stationary with respect to flux and the flux varies in magnitude with respect to time
C. Both the changes mentioned above occur together, i.e., the coil moves through a time varying field
D. All of the above

## The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?

A. minimum
B. maximum
C. nil
D. none of the above

## The design of mechanical parts is particularly important in case of __________ speed machines?

A. low
B. medium
C. high
D. any of the above

## 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

A. 0.07
B. 1.5
C. 2.5
D. 3.5

## The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?

A. minimum
B. maximum
C. nil
D. none of the above

A. upto 20 A
B. upto 40 A
C. upto 60 A
D. upto 80 A

## Disc windings are primarily used in_____________-?

A. short capacity transformers
B. medium capacity transformers
C. high capacity transformers
D. any of the above

## Direct water cooling of rotor winding presents_____________?

A. no mechanical difficulties
B. lesser mechanical difficulties
C. greater mechanical difficulties
D. none of the above

## The tiny block formed by the arrangement of a small group of atoms is called the____________?

A. unit cell
B. space lattice
C. either A. or (b)
D. none of the above

## The superconductivity is due to____________?

A. the crystal structure having no atomic vibration at 0°K
B. all electrons interact in the super-conducting state
C. the electrons jump into nucleus at 0°K
D. none of the above

## The structure sensitive property of a super conductor is______________?

A. critical magnetic field
B. transition temperature
C. critical current density
D. none of the above

## Thermocouples are mainly used for the measurement of_____________?

A. temperature
B. resistance
C. eddy currents
D. coupling co-efficient

## Thermonic emission occurs in______________?

A. vacuum tubes
B. copper conductors
C. ferrite cores
D. transistors

A. 18.0°K
B. 9.22°K
C. 4.12°K
D. 1.14’K

## The value of critical field below the transition temperature will_______________?

A. increase
B. decrease
C. remain unchanged
D. any of the above

A. Kanthal
B. Manganin
C. Nichrome
D. Eureka