An electric filament bulb can be worked from
All above
Battery supply only
A.C. supply only
D.C. supply only
All above
Resistance of a tungsten lamp as applied voltage increases
increases
remains same
decreases
none of the above
increases
Whether circuit may be AC. or D.C. one following is most effective in reducing the magnitude of the current.
Inductor
Resistor
Reactor
Capacitor
Resistor
When two D.C. generators are running in parallel an equalizer bar is used
so that the two identical machines will pass approximately equal currents to the load
to increase the series flux
to increase the generated e.m.f.
to reduce the combined effect of AR-mature reaction of both the machines
so that the two identical machines will pass approximately equal currents to the load
In a D.C. generator in order to reduce sparking at brushes the self-induced e.m.f. in the coil is neutralised by all of the following except
shifting of axis of brushes
compensating winding
interpoles
dummy coils
dummy coils
Armature coil is short circuited by brushes when it lies
along field axis
in any of the above positions
along neutral axis
in none of the above positions
along neutral axis
A cumulatively compounded long shunt generator when operating as a motor would be
differentially compounded long shunt
differentially compounded short shunt
cumulatively compounded short shunt
cumulatively compounded long shunt
differentially compounded long shunt
Number of tappings for each equilizer ring is equal to
number of pole pairs
number of parallel paths
number of poles
number of commutator segments
number of pole pairs
Which of the following statement about D.C. generators is false
Back pitch and front pitch are both odd and approximately equal to the pole pitch
Equalizing bus bars are used with parallel running of D.C. shunt generators
Compensating winding in a D.C. machine helps in commutation
In a D. C. generator interpoles winding is connected in series with the armature winding
Equalizing bus bars are used with parallel running of D.C. shunt generators
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them
just ahead of magnetic neutral axis
in magnetic neutral axis
just behind the magnetic neutral axis
none of the above
just ahead of magnetic neutral axis
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