REG NO: B
ANAND INSTITUTE OF HIGHER TECHNOLOGY
Department of EEE
COMMON TO EEE,EIE & ECE DEPARTMENT
Model Exam
Year :I Date :02.5.17
Sub Code :EE6201 Time :3 hours
Sub Name :CIRCUIT THEORY Max marks :100
PART A - (10 × 2 = 20 marks)
1. Write down the expression of equivalent resistance for ‘n’ - number of resistors in parallel
connection
2. Obtain the current in each branch of the network shown below using Kirchoff’s Current
Law.
3. Write down the formulae for converting Star to Delta
4. State Maximum power transfer theorem.
5. What are the resonant conditions?
6. Define Bandwidth, half power frequencies?
7. Define transient state and transient time
8. Define Natural response or source free response.
9. What are the advantages of 3 phase circuits over single phase circuits?
10. A delta connected load has (30-j40) ohm impedance per phase. Determine the phase
current if it is connected to 415V, three phase, and 50Hz supply.
PART B (5× 16 = 80 marks)
11. (a) (i) State and explain Kirchoff’s laws.
(ii) Using mesh analysis, determine the current through 1Ω resistor in the given circuit .
(16)
Or
(b)(i) Solve the network given below by the node voltage method.
(ii) By applying nodal analysis for the circuit shown in Fig, determine the power output of
the source and the power in each resistor of the circuit
(16)
12. (a) Obtain the Norton’s model and find the maximum power that can be transferred to the
100Ω load resistance in the circuit shown in figure
(16)
Or
(b) Find the voltage across 5Ω resistor for the circuit shown in figure a) using source
transformation technique and verify the results using mesh analysis.
(16)
13. (a) Derive the relation between coefficient of coupling& the self inductance& mutual
inductance. (16)
Or
(b)(i)With neat illustration describe the parallel resonant circuit and the equivalent parallel
network for a series RL combination.Also find the Q-factor of a parallel resonant circuit.
(ii) For the circuit below, determine the frequency at which circuit resonates. Also find
the quality factor, voltage across inductance and voltage across capacitance at resonance
(16)
14. (a) In the series RL circuit shown in fig the switch is closed on position 1 at t=0. At
t=1millisecond, the switch is moved to position Obtain the equation for current in both intervals
and draw the transient current curve
(16)
Or
(b) The switch in the circuit shown in fig is moved from position 1 to position 2 at t=0. Find
the expression for voltage across resistor and capacitor, energy in the capacitor for t>0.
(16)
15. (a) Show that three phase power can be measured by two wattmeters. Draw the phasor
diagrams. Derive an expression for power factor in terms of wattmeter readings
(16)
Or
(b)(i) A 3 phase, 3 wire 120V RYB system feeds a ∆-connected load whose phase
impedance is (221 + j 221). Find the phase and line currents in this system and draw the
phasor diagram.
(ii) If W1& W2 are the reading of two wattmeters which measures power in the three
phase balanced system and if W1/W2 = a. shows that the power factor of the circuit is
a+1
given by
√a2−a+1
cosΦ = .
(16)
