1. The graph of an electrical network has N nodes and B branches. The number of
links, L, with respect to the choice of a tree, is given by
(a) B œ N + 1 (b) B + N
(c) N œ B + 1 (d) N œ 2B -1
2. Two in-phase, 50 Hz sinusoidal waveform of unit amplitude are fed into channel 1
and channel 2 respectively of an oscilloscope. Assuming that the voltage scale,
time scale and other settings are exactly the same for both the channels, what
would be observed if the oscilloscope is operated in X-Y mode?
(a) A circle of unit radius (b) An ellipse
(c) A parabola
(d) A straight line inclined at 45° with respect to the x-axis
3. If a 400V, 50 Hz, star connected, 3 phase squirrel cage induction motor is
operated from a 400 V, 75 Hz supply, the torque that the motor can now provide
while drawing rated current from the supply?
(a) reduces (b) increases
(c) remains the same
(d) increase or reduces depending upon the rotor resistance
4. A 1 kVA, 230V/100V, single phase, 50 Hz transformer having negligible winding BDC Torque resistance and leakage inductance is operating under saturation, while 250 V, 50
Hz sinusoidal supply is connected to the high voltage winding. A resistive load is connected to the low voltage winding which draws rated current. Which one of the following quantities will not be sinusoidal?
(a) Voltage induced across the low voltage winding
(b) Core flux
(c) Load current
(d) Current drawn from the source
5. The logic circuit used to generate the active low chip select (CS) by an 8085
microprocessor to address a peripheral is shown in Fig.1.14. The peripheral will
respond to addresses in the range.
(a) E000-EFFF
(b) 000E-FFFE
(c) 1000-FFFF
(d) 0001-FFF1
6. Consider a long, two-wire line composed of solid round conductors. The radius of
A15
A14
A13
CS
A12
both conductors is 0.25 cm and the distance between their centers is 1m. If this
distance is doubled, then the inductance per unit length
(a) doubles (b) halves
(c) increases but does not double (d) decreases but does not halve
7. Consider a power system with three identical generators. The transmission losses
are negligible. One generator (G1) has a speed governor which maintains its
speed constant at the rated value, while the other generators (G2 and G3) have
governors with a droop of 5%. If the load of the system is increased, then in
steady state.
(a) generation of G2 and G3 is increased equally while generation of G1 is
unchanged.
(b) generation of G1 alone is increased while generation of G2 and G3 is
unchanged.
(c) generation of G1, G2 and G3 is increased equally.
(d) generation of G1, G2 and G3 is increased in the ratio 0.5:0.25:0.25.
8. A long wire composed of a smooth round conductor runs above and parallel to
the ground (assumed to be a large conducting plane). A high voltage exists
between the conductor and the ground. The maximum electric stress occurs at
(a) the upper surface of the conductor
(b) the lower surface of the conductor
(c) the ground surface
(d) midway between the conductor and ground
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