ELECTRICAL ENGINEERING IMPORTANT MCQ-BASIC ELECTRICAL PART FIVE

ANSWER KEY-Correct
answer is indicated by symbol (V) in options.
HINTS-In some questions options
E-HINTS is indicating the hints of answer.
 

101) .When a lead-acid battery is in fully charged condition, the colour of its positive plate
is
A [ ]) dark grey
B [ ]) brown
C [v]) dark brown
D [ ]) none of above

102) Cells are connected in series in order to
A [v]) increase the voltage rating
B [ ]) increase the current rating
C [ ]) increase the life of the cells
D [ ]) none of the above

103) The ratio of ampere-hour efficiency to watt-hour efficiency of a lead-acid cell is
A [ ]) just one
B [v]) always greater than one
C [ ]) always less than one
D [ ]) none of the above.

104) The ampere-hour efficiency of a lead acid cell is normally between
A [ ]) 20 to 30%
B [ ]) 40 to 50%
C [ ]) 60 to 70%
D [v]) 90 to 95%

105) .The capacity of a lead-acid cell does not depend on its
A [ ]) temperature
B [v]) rate of charge
C [ ]) rate of discharge
D [ ]) quantity of active material

106) The storage battery generally used in electric power station is
A [ ]) nickel-cadmium battery
B [ ]) zinc-carbon battery
C [v]) lead-acid battery
D [ ]) none of the above

107) The capacity of a battery is expressed in terms of
A [ ]) current rating
B [ ]) voltage rating
C [v]) ampere-hour rating
D [ ]) none of the above

108) Trickle charging of a storage battery helps to
A [ ]) maintain proper electrolyte level
B [ ]) increase its reserve capacity
C [ ]) prevent sulphation
D [v ]) keep it fresh and fully charged

109) As compared to a lead-acid cell, the efficiency of a nickel-iron cell is less due to its
A [ ]) compactness
B [ ]) lower e.m.f.
C [ ]) small quantity of electrolyte used
D [v]) higher internal resistance

110) The output voltage of a charger is
A [ ]) less than the battery voltage
B [v]) higher than the battery voltage
C [ ]) the same as the battery voltage
D [ ]) none of the above

111) The watt-hour efficiency of a lead-acid cell varies between
A [ ]) 25 to 35%
B [ ]) 40 to 60%
C [v]) 70 to 80%
D [ ]) 90 to 95%

112) In ______ system the charging current is intermittently controlled at either a maximum
or minimum value
A [v]) two rate charge control
B [ ]) trickle charge
C [ ]) floating charge
D [ ]) an equalizing charge

113) When the specific gravity of the electrolyte of a lead-acid cell is reduced to 1.1 to 1.15
the cell is in
A [ ]) charged state
B [v]) discharged state
C [ ]) both (A) and (B)
D [ ]) active state

114) .The effect of sulphation is that the internal resistance
A [v]) increases
B [ ]) decreases
C [ ]) remains same
D [ ]) none of the above

115) The specific gravity of electrolyte is measured by
A [ ]) manometer
B [ ]) a mechanical gauge
C [v]) hydrometer
D [ ]) psychrometer

116) Each cell has a vent cap
A [ ]) to allow gases out when the cell is on charge
B [ ]) to add water to the cell if needed
C [ ]) to check the level of electrolyte
D [v]) to do all above functions

117) The open circuit voltage of any storage cell depends wholly upon
A [ ]) its chemical constituents
B [ ]) on the strength of its electrolyte
C [ ]) its temperature
D [v]) all above

118) Over charging
A [ ]) produces excessive gassing
B [ ]) loosens the active material
C [ ]) increases the temperature resulting in buckling of plates
D [v]) all above

119) Internal short circuits are caused by
A [ ]) breakdown of one or more separators
B [ ]) excess accumulation of sediment at the bottom of the cell
C [v]) both (A) and (B)
D [ ]) none of the above

120) .Excessive formation of lead sulphate on the surface of the plates happens because of
A [ ]) allowing a battery to stand in discharged condition for a long time
B [ ]) topping up with electrolyte
C [ ]) topping up with electrolyte
D [ ]) low level of electrolyte
E [v]) all of above
 
121) .Undercharging
A [v]) reduces specific gravity of the electrolyte
B [ ]) increases specific gravity of the electrolyte
C [ ]) produces excessive gassing
D [ ]) increases the temperature

122) If a battery is wrongly connected on charge following will happen
A [ ]) current delivered by the battery will be high
B [ ]) current drawing will be nil
C [ ]) current drawing will be very small
D [v]) current drawing will be very high

123) In constant-current charging method, the supply voltage from discharged to fully
charged condition
A [ ]) decreases
B [v]) increases
C [ ]) remains constant
D [ ]) none of the above

124) .Level of electrolyte in a cell should be _____ the level of plates
A [v]) below
B [ ]) equal to
C [ ]) above
D [ ]) none of the above

125) .Cell short circuit results in
A [ ]) low sp. gravity electrolyte
B [ ]) abnormal high temperature
C [ ]) reduced gassing on charge
D [v]) all above

126) Internal resistance of a cell is reduced by
A [ ]) using vent plug to permit gas formed during discharge
B [ ]) increasing the plate area
C [ ]) putting plates very close together
D [v]) all above methods

127) Following will happen if battery charging rate is too high
A [ ]) excessive gassing will occur
B [ ]) temperature rise will occur
C [ ]) bulging and buckling of plates will occur
D [v]) all above will occur

128) .Under normal charging rate, the charging current should be
A [v]) 10% of capacity
B [ ]) 20% of capacity
C [ ]) 30% of capacity
D [ ]) 40% of capacity

129) Cells are connected in parallel to
A [ ]) increase the efficiency
B [v]) increase the current capacity
C [ ]) increase the voltage output
D [ ]) increase the internal resistance

130) .When two batteries are connected in parallel, it should be ensured that
A [v]) they have same e.m.f.
B [ ]) they have same make
C [ ]) they have same ampere-hour capa-city
D [ ]) they have identical internal resistance

131) Thevenin resistance Rth is found
A [ ]) by removing voltage sources along with their internal resistances
B [ ]) by short-circuiting the given two terminals
C [ ]) between any two ‘open’ terminals
D [ ]) between same open terminals as for Equivalent

132) In Thevenin’s theorem, to find Z
A [ ]) all independent current sources are short circuited and independent voltage sources are
open circuited
B [ ]) all independent voltage sources are open circuited and all independent current sources are
short circuited
C [ ]) all independent voltage and current sources are short circuited
D [v]) all independent voltage sources are short circuited and all independent current sources are
open circuited

133) A bilateral networks having independent voltage or current source is replaced by a
singe voltage source in series with single equevalent resistance is known as
A [ ]) NORTONS THEOREMS
B [ ]) SUPERPOSITION THEOREMS
C [v]) THEVENINS THEOREMS
D [ ]) ALL OF ABOVE

134) A bilateral networks having independent voltage or current source is replaced by a
singe current source in parrallel with single equevalent resistance is known as
A [ ]) Thevenins theorem
B [ ]) Maximum power theorem
C [v]) Nortons theorems
D [ ]) Non og above

135) which one is Joules law
A [ ]) H=VIt
B [ ]) H=Wt
C [ ]) H=I²Rt
D [v]) all of above
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EE AND ECE IMPORTANT MCQ-COMMUNICATION SYSTEMS PART ONE
ELECTRICAL ENGINEERING IMPORTANT MCQ-BASIC ELECTRICAL PART FOUR

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