October 2023

Q. The Fourier transform of a signal 𝑥(𝑡), denoted by 𝑋(𝑗w), is shown in the figure. Let 𝑦(𝑡) = 𝑥(𝑡) + 𝑒𝑗𝑡𝑥(𝑡). The value of Fourier transform of 𝑦(𝑡) evaluated at the angular frequency w= 0.5 rad/s is (A) 0.5                        (B) 1                           (C) 1.5                       (D) 2.5 Ans: 1.5

Q. In the given circuit, the mesh currents I1, I2 and I3 are (A) I1 = 1 A, I2 = 2 A and I3 = 3 A                 (B) I1 = 2 A, I2 = 3 A and I3 = 4 A (C) I1 = 3 A, I2 = 4 A and I3 = 5 A                

Q. In the figure, an RLC load is supplied by a 230 V, 50 Hz single phase source. The magnitude of the reactive power (in VAr) supplied by the source is Ans: 66-68

Q. In the given circuit, superposition is applied. When V2 is set to 0 V, the current I2 is -6 A. When V1 is set to 0 V, the current I1 is +6 A. Current I3 (in A) when both sources are applied will be (up to two decimal places) . Ans: 0.95-1.05

Q. In the given circuit, superposition is applied. When V2 is set to 0 V, the current I2 is -6 A. When V1 is set to 0 V, the current I1 is +6 A. Current I3 (in A) when both sources are applied will be (up to two decimal places) Ans: 0.95-1.05

Q. Two bags 𝐴 and 𝐵 have equal number of balls. Bag 𝐴 has 20% red balls and 80% green balls. Bag 𝐵 has 30% red balls, 60% green balls and 10% yellow balls. Contents of Bags 𝐴 and 𝐵 are mixed thoroughly and a ball is randomly picked from the mixture. What is the

Q. An optical pulse containing 6 × 106 photons is incident on a photodiode and 4.5 × 106 electron-hole pairs are created. The maximum possible quantum efficiency (in %) of the photodiode is Ans: 75 Sol: Number of incident photons ′N′=6×106 Number of electron-hole pairs generated n=4.5×106 Quantum efficiency of photo-diode

Q. An amplitude modulated signal is shown in the figure. The modulation index is (up to one decimal place) . Ans: 0.3

Q. A piezoelectric pressure sensor has a bandpass characteristic with cut-off frequencies of 0.1 Hz and 1 MHz, and a sensitivity of 100 mV/kPa. The sensor is subjected to a static constant pressure of 100 kPa. Its steady-state output will be (A) 0 V                       (B) 0.1 V                    (C) 1 V                       (D) 10 V Ans: 0.V  

Q. As shown in the figure, temperature q is measured using a K type thermocouple. It has a sensitivity of 40 mV/°C. The gain (G) of the ideal instrumentation amplifier is 25. If the output Vo is 96 mV, then the value of q (in °C) is _ . Ans: 95-97