Basic circuit theory (INDSC1B) — DU B.Sc. (Hons) Instrumentation Previous Year Question Papers

Q.1 (a) Two resistances Ri and R2 when connected in series, the effective value of 3 resistance are 80Q. When connected in parallel the effective value is 20Q. Calculate the value of resistance Ri and R2. (b) Define the term power factor. What is its value for a purely reactive load? 3 (c) Calculate the cut-off frequency of an Rc low-pass filter having R=10kQ and 3 (d) (e) Draw the frequency response of series RLC circuit. 3 Two resistors 4Q and 6Q are connected in parallel as shown in Fig.1. Find the 3 current through each resistor when total current is 12A. Define time constant for RL circuit. Draw the transient current characteristics. 3 Q.2 (a) Findthe current passing through 3Q resistor for the circuit shown below in Fig.2 7 by using superposition theorem? (b) For the circuit shown in Fig.3. Find the total capacitance and voltage across each 6 Q.3 (a) Writethe mesh current equations in the circuit shown in Fig.5 and detemine the 7 currents flowing through 2Q resistor. (b) Calculate the voltages at node A and B using nodal analysis for given circuit 7 shown in Fig.6. (c) Discuss the quality factor (Q) in parallel RLC circuit. Q.4 (a) Verify the reciprocity theorem by determining the value of I for the given network in Fig.7. (b) By applying Norton's Theorem, Find the current through 29 resistor as shown in 6 (c) Convert the given circuit shown in Fig.9 into the Thevenin equivalent circuit. 5 Q.5 (a) Derive the step response of RC circuit. 7 (b) Explain the working of low pass filter with diagram. Draw its frequency response. 6 (c) Find the equivalent impedance between terminal A and B in polar form in Fig. 10. 5 Q.6 (a) For an AC circuit, a voltage source vt) = 120 cos(100mt+30°)V is connected to a 8 oad and the resulting current is i(t) = 5 cos(100ttt -15°)A. Find the averag ower, reactive power, complex power and apparent powel (b) A two port network has the following parameters: Z11=452, Z12 = 152, Z21=3 S and Zz= 32. Calculate short circuit parameters (Y) and h-parameters. (c) Find Z-parameters for following circuit shown in Fig.11. 4 Q.7 (a) Determine the maximum power that can be transferred to the load resistance (RL) 6 in the given circuit shown in Fig.12. (b) In the given circuit in Fig. 13, the switch has been in position A for a long time. At y t=0, switch moves to position B. Determine V (t) for t>0 and calculate its value at t= 3sec. (* Vows ig 14s Theorem, find the current in the 102 resistor for the circuit 20v +L sove SOV