4. A bulb in a staircase has two switches, one switch being at the ground floor and the other at the first floor. The bulb can be turned ON and also be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles
a) an AND gate
b) an OR gate
c) an XOR gate
d) a NAND gate
5. For periodic signal v(t)= 30 sin 100t+ 10cos 300t+ 6 sin(500t+π/4), the fundamental frequency in rad/s is
a) 100
b) 300
c) 500
d) 1500
6.A band-limited signal with a maximum frequecy of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency in kHz which is not valid is
a) 5
b) 12
c) 15
d) 20
8. The angle δ in the swing equation of a synchronous generator is the
a) angle between stator voltage and current.
b) angular displacement of the rotor with respect to the stator.
c) angular displacement of the stator mmf with respect to a synchronously rotating axis.
d) angular displacement of an axis fixed to the rotor with respect to a synchronously rotating axis.
9. Leakage flux in an induction motor is
a) flux that leaks through the machine.
b) flux that links both stator and rotor windings.
c) flux that links none of the windings.
d) flux that links the stator windings or the rotor winding but not both.
18. Which one of the following statements is NOT TRUE for a contiunous time casual and stable LTI system?
a) All the poles of the system must lie on the left side of the jw axis.
b) zeros of the system can lie anywhere in the s-plane.
c) all the poles must lie within mod s =1
d) all the roots of the characterstic equation must be located on the left side of the jw axis.
19.Two systems with impulse responses h1(t) and h2(t) are connected in cascade. Then the overall impulse response of the cascaded system is given by
a) product of h1(t) and h2(t)
b) sum of h1(t) and h2(t)
c) convolution of h1(t) and h2(t)
d) subration of h2(t) and h1(t)
20. A source Vs(t) = V cos 100πt has an internal impedence of (4+j3) Ohm. If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in Ohm should be
a) 3
b) 4
c) 5
d) 7
