78.

79.

80.

81.

82.

83.

84.

85.

86.

87.

The aquadag coating in CRO is used to collect
(A) _ primary electrons (B) secondary emission electrons
(0 ‏طامط‎ (A) and (8) (D) None of the above

The sweep generator of a CRO is used to produce
(A) ൧ sawtooth voltage for the horizontal deflection of electron beam.
(B) A sinusoidal voltage for the vertical deflection of the electron beam
(೮) ൧ sinusoidal voltage for the horizontal deflection of the electron beam
(D) A sawtooth voltage for the vertical deflection of the electron beam

A moving coil ammeter has a uniform scale with 100 divisions and gives full scale
reading of 10 A. The instrument can read upto 1/5" of a scale division with a fair degree
of certainity. Determine the resolution of the instrument in amperes.

(A) 0.01A (8) 0.04 &
(൭ ۸ (ಐ) 0.03 ^

Which of the following system has memory ?
(^) y(t) = x(t) (8) y(t) = tr(t) + 2x(t)
(C) y(t) =ax(t)—b (0) y(t) =x(t) + x(t- I)

A signal has a spectrum ranging from 0 to 15 kHz is to be sampled to be converted to
discrete form. What is the minimum number of samples per second that must be taken to
ensure recovery ?

(A) 7,500 samples /second (B) 30,000 samples /second

(C) 15,000 samples/second (D) 60,000 samples /second

Determine the fundamental period of the following signal :
x(n) =10cos(0.27n)
(A) 10 (B) 5
(൭ 15 (D) 20
A system is described by T[x(n)] = g(n) x(n).
Which of the following is correct for the system ?

(A) Non-linear (B) Time invariant
(0) Memoryless (D) Non casual
Check the casuality and stability of the following system :
h(n) = (0.5
(A) Non casual and 8180 stable (B) Casual and BIBO stable
(C) Casual and unstable (D) Non casual and unstable

A necessary and sufficient condition for BIBO stability of discrete time LTI system is that
(^) Magnitude of every root of its characteristic equation must be > 1
(B) Magnitude of every root of its characteristic equation must be < 1
(C) Magnitude of every root of its characteristic equation must be = 1
(D) Magnitude of every root of its characteristic equation must be 2 |

The system is linear if it is
(A) homogeneous (B) additive
(C) additive and homogeneous (D) _ time invariant

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2.70.)