EEE IMP QUESTION

EEE IMP QUESTION

1 State and explain Kirchhoff’s laws. (KVL & KCL)

2 Derive and obtain the expression for temperature co efficient of resistance. α2=1/(1/ α1 +(t2-t1))

3 The resistance of a coil embedded in a large transformer is 12 Ω at 25 ̊C after the transformer has been in operation for several hours, the resister of the coil found to be 13.4Ω. Find the Temperature the transformer core. Take α 20 = 0.00393 ̊ C-1

4 Compare series and parallel resonance.

5 Compare the following term with respect to ac waveform. (1)Power factor (2) Average value (3) R.M.S value (4) Form factor

6 A Series RLC circuit consists of resistance of 500 Ω, inductance of 50mHand a capacitance Of 20pF. Find (1) the resonant frequency (2) The Q factor of the circuit of resonance (3) The half power frequency

7 State Colum’s law of electrostatics

8 Give similarities and dissimilarities between electrical circuit and magnetic circuit.

9 Obtain the relation L=(L1L2-M2) / (L1+L2+2M) for equivalent inductance when two inductors are connected in parallel such that the mutual induced emf opposes the self induced emf.

10 Explain magnetic hysteresis.

11 State and explain Faraday’s law of electromagnetic induction

12 Find resistance between terminals AB of network shown in figure. 1 using star-delta transformation

13 Explain how ac sinusoidal emf is generated?

14 Derive equation for energy stored in capacitor.

15 Explain in brief power measurement using two wattmeter method in 3-phase system with star connected load?

16 List the different types of illumination scheme

17 Define cable and explain its construction with neat sketch diagram

18 List the different types of lamp and explain florescent lamps with wiring diagram.

19 Analyze Series and parallel circuit having resistors only as elements and state the results.

20 Derive the equations to translate a passive electric circuits from star network to delta network configuration with diagram.

21 A capacitor of 0.1 μF is charged from a 100 V battery through a series resistance of 1000 Ω. Find: [1] Time constant [2] Charge received during this time [3] Initial rate of charging [4] the rate of charging when the charge is 63.2 % of final charge.

22 Analyze the series and parallel connection of capacitor and prove the equations. Also find out the equation for energystored in capacitor.

23 If a coil of 150 turns is linked with a flux of 0.01 Wb , when carrying a current of 10 A. Calculate: [1] the inductance of the coil [2] the induced e.m.f , if this current is uniformly reversed in 0.01 second.

25 A resistance of 20 Ω, an inductance of 0.2 H and a capacitance of 100 μF are connected in series across 220 V, 50 Hz

supply. Find:

[1] Impedance [2] Voltage across R,L & C [3] Power factor & angle of lag [4] Active & apparent power

26 Prove the condition of resonance for R-L-C series AC circuit. Also analyze the phenomena with the help of graph.

27 Explain in brief the following for 3-phase AC circuit : [1] Phase sequence [2] Line voltage [3] Phase voltage

28 A Δ-connected balanced 3-phase load is supplied from 400 V , 3-phase mains. The line current is 20 A & the power taken

by load is 10 MW. Find :

[1] Impedance in each branch [2] Power factor of the load [3] Line current & power consumed, if same load is connected in star.

29 Explain in brief the following.[1] A-h & W-h capacity of a battery [2] Rating of MCB [3] Lumens

30 Discuss the types of cables used for residential and commercial wiring.

31 What do you mean by earthing ? Analyze earthing concept with the help of a device-ELCB ( Earth leakage circuit breaker ) used at our residence

32 List out types of lamps and explain fluorescent lamp in detail.

33 Define Temperature co-efficient of resistance. Derive & obtain the expression α2 = 1/(1/α1 + (t2 - t1)) with usual notation

34 Explain how ac sinusoidal emf is generated? Derive its equation of e = EmSinωt.

35 An ac supply voltage of 230 volts, 50 Hz is given to the circuit containing 10Ω and 20Ω in series. Find equivalent resistance, total current, and voltage drop across each resistance, active power, reactive power, power factor.

36 Define co-efficient of coupling. Derive the relation between self and mutual inductance.

37 A coil has 1000 turns and carries a current of 5 Amp. The core has a length of 0.5 m and cross-sectional area of 80 cm2, relative permeability is 1000. Calculate self inductance and self induced emf when current is switched off in 0.01 sec

38 Define term ‘earthing’. State all the methods of earthing and explain any one of them.

39 Capacitors having capacitance of 10 μF, 20 μF and 30 μF are connected in series to a 400 V dc source. Find: 1) total capacitance of circuit 2) total charge stored in the circuit 3) total energy stored in the circuit.

40 Establish relationship between line and phase voltages and currents in balanced delta connection. Draw complete phasor diagram of voltages and currents.

41 Explain series resonance circuit. Draw resonance curve.

42 An inductive coil of resistance R and inductance L is connected in parallel with capacitor of C. Derive an expression for the resonant frequency and Q factor.

43 An iron ring has mean diameter of 57.3 cm. It carries a coil having 450 turns and the current flowing through coil is 2 A. The relative permeability of the iron is 1200. Calculate the flux density produced.

44 Three capacitors having capacitances of 10 μ F, 20 μ F and 40 μF are connected in series to a 400 V d.c. source. Find (i) total capacitance (ii) total charge in circuit (iii) total energy stored.

45 Derive the expression for the decay of current in an inductive circuit. Define time constant.

46 A coil resistance 15 Ωand inductance 0.05 H is connected in parallel with a noninductive resistance of 20 Ω. The circuit is connected across 200 V, 50 Hz supply. Determine (i) current in each branch (ii) total current supplied (ii) power factor of the combination.

47 A delta connected load having branch impedances of (15 +j20) Ωis connected to a220V, 3 phase AC supply. Find

a. Line currents. b. Per phase power consumed. c. What is the phasor sum of the line currents? Why does it have this value?

48 Explain construction of cable in detail.

49 Short note on ELCB

50 Explain waveform of series R-C circuit with power equation.