Related Questions

Two circular dials of exactly the same size are mounted on a wall side by side in such a way that their perimeters touch at one point. Dial 1, which is on the left , spins clockwise around its center , and dial 2 , which is on the right spins counter clockwise around its center . (Assume that there is no friction at the point of contact between the dials.) Each dial is marked on its perimeter at three points that are at equale distances around the points arked ondial 1 are N, O, and P and the points marked on dial 2 are X, Y, and Z. If points O and Z are just meeting at the point of contact between the dials , and if dial 1 spins at the same speed as dial 2, what is the smallest number of revolutions of each dial that will bring O and Z together again?
A 1
B 2
C 3
D 4
The sparking between two electrical contacts can be reduced by inserting a
A capacitor in parallel with contacts
B capacitor in series with each contact
C resistance in line
D none of the above
In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have
A Low density
B Low temperature
C Long ignition delay
D All of these
The advancing of spark timing in spark ignition engines will _________ knocking tendency.
A Increase
B Reduce
C Not effect
D None of these
If the air-fuel mixture ignites before the spark takes place at spark plug, the condition is called
A Detonation
B Ignition
C Pre-ignition
D Rumble
Sparking at the commutator of a D.C. motor may result in
A Damage to commutator segments
B Damage to commutator insulation
C Increased power consumption
D All of the above
Sparking, is discouraged in a D.C. motor because
A It increases the input power consumption
B Commutator gets damaged
C Both (A) and (B)
D None of the above
Sparking occurs when a load is switched off because the circuit has high
A Resistance
B Inductance
C Capacitance
D Impedance
In a universal motor, the most common cause of brush sparking is
A open armature winding
B shorted armature winding
C shorted field winding?
D high commutator mica
E all of the above
In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralized by all of the following except
A Interpoles
B Dummy coils
C Compensating winding
D Shifting of axis of brushes

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