Rajiv Gandhi Proudyogiki Vishwavidyalaya 2009-3rd Sem B.E Electronics & Tele-Communication Engineering Model ester, electrical & electronics engineering - Question Paper

ELECTRIC CIRCUIT THEORY

Time : three hours Maximum Marks : 100

PART – A
ans all ques. - every ques. carries four marks

(1) Compare and differentiate unilateral and bilateral systems. Can you apply reciprocity theorem to these?
(2) List the necessary conditions for driving point and transfer functions.
(3) Two coupled coils have K = 0.8, N1 = 500 turns, N2 = 1000 turns and the mutual flux being 0.9Wb, obtain the primary coil flux. If the primary current is 10A, obtain the primary coil inductance. Also find the secondary inductance.
(4) In a transformer, K = 0.8, the mutual inductance = 10 H, the no. of primary and secondary turns are 50 and 200. find the value of the primary current to produce 0.5Wb flux to link with the secondary coil. Also, compute the value of secondary current.
(5) State and discuss Superposition theorem.
(6) 3 resistors R12, R23 and R31 are delta connected. Derive expressions for R1, R2 and R3 in equivalent star connected network.
(7) From basics find an expression for the potential difference ranging from star point of the load and supply neutral. Can this be greater than supply line voltage? discuss
(8) Substantiate the statement "A polyphase system is like a multicylinder engine."
(9) Explain how to develop a tieset matrix for a provided graph.
(10) List out the applications of MATLAB.
(10 x four = 40 marks)
PART – B
ans all ques. - every ques. carries 12 marks.

(11) obtain the power dissipated in the 5? resistor shown in the figure beneath using mesh analysis. (12 marks)

OR
(12) obtain the node voltages by node voltage analysis method. (12 marks)

(13) Write the mesh equations for the network shown in figure. (12 marks)

OR
(14) obtain the drop across the capacitor and the resistor. (12 marks)

(15) find the equivalent resistance for the network. All resistors are of 100????????? (12 marks)

OR
(16) Determine current through 3??resistor using Norton's theorem for the network shown. (12 marks)

(17) The total power supplied to 3 similar resistors connected in (a) Y (b) from a balanced 3? source is P. 1 of the resistors burn out. (i) Derive the expressions for power in terms of P for both cases. Hence (ii) compute the power taken from the supply system when 3 100? non inductive resistances are connected in (a) Y (b) across a 400V, 50Hz, 3??mains. (iii) In the event 1 of the resistances burn out, what would be the value of total power taken from the mains in every of the 2 cases?
(12 marks)
OR
(18) 3 impedances of ZR = 10 + j10 ??? ZY = 20 + j20 ??and ZB = 0 – j10 ?? are respectively star connected to a 3?, 400V symmetrical system of phase sequence RYB. obtain (i) the star point potential (ii) voltage drop across every impedance (iii) the current in every supply line (iv) phase angle ranging from the currents and corresponding line voltages (v) total real, reactive and apparent powers supplied to the load (vi) complete vector diagram of voltages and currents (vii) a balanced delta connected resistors which would take the identical power. (12 marks)

(19) For the graph shown in figure below, choose a tree T {5,6,7,8,9}.Show all the fundamental cutsets Write down the cutset matrix. find network equilibrium formula. How can these KCL equations be simulated in MATLAB? (12 marks)

OR
(20) With help of an example, show how P spice can be used for the electric circuit analysis. (12 marks)

(12 x five = 60 marks)

Earning:   Approval pending.