Electrical Engineering GATE 2020 Questions with Answer

Ques 1 Analog Circuits

A common-source amplifier with a drain resistance, R_D=4.7 kΩ, is powered using a 10 V power supply. Assuming that the transconductance, g_m, is 520 µA/V, the voltage gain of the amplifier is closest to:

Ques 2 Circuit Theory

Currents through ammeters A2 and A3 in the figure are 1∠10° and 1∠70°, respectively. The reading of the ammeter A1(rounded off to 3 decimal places) is ________ A.

Ques 3 Circuit Theory

The Thevenin equivalent voltage, V_TH in V (rounded off to 2 decimal places) of the network shown below, is ________.

Ques 4 Circuits

Consider the diode circuit shown below. The diode, D, obeys the current-voltage characteristic I_D = I_S(exp(V_D / nv_T) - 1), where n > 1, V_T > 0, V_D is the voltage across the diode and I_D is the current through it. The circuit is biased so that voltage, V > 0 and current, I < 0.
If you had to design this circuit to transfer maximum power from the current source (I₁) to a resistive load (not shown) at the output, what values of R₁ and R₂ would you choose?

Ques 5 Circuits

A benchtop de power supply acts as an ideal 4 A current source as long as its terminal voltage is below 10 V. Beyond this point, it begins to behave as an ideal 10 V voltage source for all load currents going down to 0 A. When connected to an ideal rheostat, find the load resistance value at which maximum power is transferred, and the corresponding load voltage and current.

Ques 6 Circuits

A resistor and a capacitor are connected in series to a 10 V de supply through a switch. The switch is closed at t=0, and the capacitor voltage is found to cross 0 V at t=0.4τ, where is the circuit time constant. The absolute value of percentage change required in the initial capacitor voltage if the zero crossing has to happen at t=0.2τ is _______ (rounded off to 2 decimal places).

Ques 7 Circuits

Windings 'A', 'B', and 'C' have 20 turns each and are wound on the same iron core as shown, along with winding 'X' which has 2 turns.
The figure shows the sense (clockwise/anti-clockwise) of each of the windings only and does not reflect the exact number of turns.
If windings A, B, and C are supplied with balanced 3-phase voltages at 50 Hz and there is no core saturation, the no-load RMS voltage (in V, rounded off to 2 decimal places) across winding 'X' is ___________.

Ques 8 Circuits

The temperature of the coolant oil bath for a transformer is monitored using the circuit shown. It contains a thermistor with a temperature-dependent resistance, R_thermistor = 2(1 + α T), where T is the temperature in °C. The temperature coefficient, α, is −(4 ± 0.25) /°C.
Circuit parameters: R₁ = 1 kΩ, R₂ = 1.3 kΩ, R₃ = 2.6 kΩ.
The error in the output signal (in V, rounded off to 2 decimal places) at 150°C is _______.

Ques 9 Control Systems

Consider a linear time-invariant system whose input r(t) and output y(t) are related by the following differential equation:
d²y(t)/dt²+4y(t)=6r(t)
The poles of this system are at

Ques 10 Control Systems

Which of the options is an equivalent representation of the signal flow graph shown here?

A

B

C

D

Ques 11 Control Systems

Consider a negative unity feedback system with forward path transfer function G(s) = K / ((s + a)(s - b)(s + c)), where K, a, b, and c are positive real numbers.
For a Nyquist path enclosing the entire imaginary axis and right half of the s-plane in the clockwise direction, the Nyquist plot of (1 + G(s)) encircles the origin of the (1 + G(s)) plane once in the clockwise direction and never passes through this origin for a certain value of K.
Then, the number of poles of G(s) / (1 + G(s)) lying in the open right half of the s-plane is __________.

Ques 12 Control Systems

Consider a permanent magnet de (PMDC) motor which is initially at rest. At t=0. a de voltage of 5 V is applied to the motor. Its speed monotonically increases from 0 rad/s to 6.32 rad/s in 0.5 s and finally settles to 10 rad/s. Assuming that the armature inductance of the motor is negligible, the transfer function for the motor is

Ques 13 Control Systems

Which of the following options is correct for the system shown below?