ISRO 2018 EC Mini Mock 2 (Full Syllabus) for ESE & GATE EC Exams

Question 1

An NPN transistor has a beta cut off frequency

of 1 MHz, and a common emitter short circuit low frequency current gain

of 200, its unity gain frequency

and the alpha cut-off frequency

respectively are

Question 2

With the introduction of negative feedback, the gain-bandwidth product of an amplifier?

Question 3

A low-pass signal having a bandwidth of 3500 Hz is sampled such that a guard band is available for ease in filtering. The sampling frequency used in 7500 Hz. The guard bandwidth is

Question 4

In a binary PCM system, the maximum tolerable error in sample amplitudes is 0.25% of the peak input signal amplitude. The input signal bandwidth is 5 MHz’s The minimum rate of transmission of the PCM coded bits is

Question 5

The characteristics equation of a closed loop control system is given as s² + 4s +16 = 0. The resonant frequency in radian/sec of the system is

Question 6

OLTF of an unity feedback system

. for complex roots, the RLD is circle of centre, whose co–ordinates are

Question 7

Consider the circuit given below

The output of each converter is given to adder which adds them considering decimal number. The output of adder is S. The value of S is_____________.

Question 8

The number of states in a 5 bit ring, 5 bit Johnson counter and the number of unused states in a 5 bit ring, Johnson counter

Question 9

An antenna has a radiation resistance of 50 Ω and a loss resistance of 10 Ω. If the power gain of antenna is 20, the directive gain of the antenna is given by

Question 10

A parallel-plate guide operates in the TEM mode only over the frequency range 0<f<3 GHz If the dielectric between the plates is Teflon (

then maximum allowable plate separation b is: -

Question 11

A metal-semiconductor junction is taken. The variation of the electric field inside the semiconductor is shown in the figure below

The built-in potential of the diode is _____V.

Question 12

The following logic families have their propagation delay. Arrange them from lowest propagation delay to highest propagation delay
1) TTL (Standard)
2) ECL
3) Low power CMOS
4) DTL

Question 13

An experiment succeeds twice as often as it fails. Find the chance that in the next four trials, there shall be at least one success.

Question 14

For a given matrix A of order 3, |A| = 60 and two of its Eigen values are 3 and 5. The sum of its Eigen values is:

Question 15

A DC voltmeter has a sensitivity of 100 ohm/Volt. When it measure half full scale in 10 V range, the current in mA through the voltmeter will be in :

Question 16

A high swamping resistance is often connected in series with the coil of the ammeter. What is the purpose of using this swamping resistance?

Question 17

A impulse response of a system is described by

. Determine the magnitude of H(z) at

.

Question 18

Compute the system’s response to the input x[n] =

| if the unit impulse response h[n] of a DT LTI system is h[n]= δ[n-1]?

Question 19

In the given network, initially the switch is in the position 1, but at t = 0, the switch is moved to position 2 and the capacitor starts discharging. Find the discharging current i(t).

Question 20

The Z-parameters of a two-port network are:

When converted in terms of the T-parameters, the parameters were obtained as,

Determine the value of variables in Z-parameter matrix.