Electrical Eng. · Question Bank

Energy Conversion

357 questions · page 1 of 18. Answer in your head first, then check the solution.

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#1
What is the usual value of the leakage coefficient for electrical machines?
A0.5 to 1
B1 to 5
C5 to 10
D1.15 to 1.25
#2
A _____ is a group of cells that generate electric energy from their internal chemical reaction
Abattery
Bregulator
Cpower supply
Dsolar array
#3
Which of the following is the main function of a battery?
Ato provide a source of steady dc voltage of fixed polarity
Bto provide a source of steady dc voltage of variable polarity
Cto provide a source of variable dc voltage of fixed polarity
Dto provide a source of variable dc voltage of variable polarity
#4
The volt is a unit of
Aelectromotive force
Benergy
Cforce
Dmagnetomotive force
#5
A transformer will work on
Aac only
Bac as well as dc
Cdc only
Dpulsating dc
#6
In a chemical cell, current is the movement of
Apositive and negative ions
Bpositive charges
Cpositive ions only
Dnegative ions only
#7
What is the nominal output of an automotive battery having six lead-acid cells in series?
A12 V
B24 V
C6 V
D3 V
#8
The speed of a dc motor is
Adirectly proportional to flux per pole
Binversely proportional to flux per pole
Cinversely proportional to applied voltage
Dinversely proportional to armature current
#9
Low-speed alternators are driven by
Ahydraulic turbines
Bdiesel engines
Chydraulic engines
Ddiesel engines
#10
High-speed alternators are driven by
Adiesel engines
Bstream turbines
Chydraulic turbines
Ddiesel engines
#11
The common 9-V flat battery for transistor radio has _____ cells connected in series.
Atwelve
Bthree
Csix
Dnine
#12
For the same rating, the size of low-speed alternator is _____ that of high-speed alternator.
Aabout the same as
Bless than
Cmore than
Dtwice
#13
Which of the following is not a secondary cell?
ASilver-Zinc
BNickel-iron
Csilver oxide
Dlead-acid
#14
Which of the following is not a primary cell?
Acarbon-zinc
Bzinc chloride
Cedison cell
Dmercuric acid
#15
The brush voltage drop in a dc machine is about
A0.1 V
B2 V
C10 V
D20 V
#16
Carbon brushes are used in a dc machine because
Acarbon lubricates and polishes the commutator
Bcontact resistance is decreased
Ccarbon is cheap
Dcarbon is abundant
#17
Considered as the main types of battery
Alithium cell and alkaline
Bcarbon-zinc dry cell and lead-sulfuric wet cell
Cleclanche cell and carbon-zinc
Dvoltaic cell and lithium cell
#18
Which of the following is the main function of a dc motor?
Ato generate power
Bto change mechanical energy to electrical energy
Cto change electrical energy to mechanical energy
Dto change chemical energy to mechanical energy
#19
Which motor has the best speed regulation?
Aseries
Bshunt
Ccommulatively compounded
Ddifferentially compounded
#20
A method of converting chemical energy into electrical energy by dissolving two different conducting materials in an electrolyte.
Abattery
Bcell
Cvoltaic cell
Dcharging

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