 MORE IN Basic Electrical & Electronics Engg
MU First Year Engineering (Semester 1)
Basic Electrical & Electronics Engg
December 2016
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1(a) Find equivalent resistance across the terminal AB.
!mage
3 M
1(b) Find load resistance which dissipate maximum power.
3 M
1(c) Find the rms value of a sinusoidal waveform.
3 M
1(d) Draw resonance graph and write any four conditions of series reasonance.
3 M
1(e) Write equations for three phase active power ans reactive power along with its units.
2 M
1(f) Derive the conditions for maximum efficiency of a single phase transformer.
4 M
1(g) Draw the input and output voltage waveform of a half wave rectifier.
2 M

2(a) Using Mesh analysis find current through 2Ω resistor.
!mage
6 M
2(b) The impedances (12) Ω and (10-j20) Ω are connected in parallel and current through 12Ωis 10<0. Determine current through other branch, total current and kVA, kVAR, kW and power factor of the whole circuit.
8 M
2(c) Draw phasor diagram of a single phase transformer connected to a inductive load.
6 M

3(a) In a delta connected load each phase consists of a resistance of 100Ω in series with a capacitor of capacitance 31.8μF. When it is connected to a 400 V, three phase 50Hz supply calculate < br> i) the line current ii) Power factor iii) The power absorbed and iv) total kVA.
8 M
3(b) A 50 kVA, 2200/220V, 50 Hz single phase transformer gave the following test results. Open circuit test(H.V side): 2200 V, 0.5A, 1000W
Short circuit test (H.V side): 100V, 20 A, 500 W
Determine i) Half load efficiency at 0.8 pf lagging and
ii) KV A at which maximum efficiency occurs and maximum efficieny at unity power factor
6 M
3(c) With neat circuit diagram and characteristics explain the input and output characteristics of a CE transistor configuration.
4 M
3(d) Draw the circuit diagram and output voltage waveform of a full wave bridge rectifier with capacitor filter.
2 M

4(a) Find current through 10Ω using source transformation.
!mage
7 M
4(b) A balanced three phase star connected load has an impedance of 50<60Ω each phase connected across a three phase 1100 V, 50Hz supply. Two watt meters are used to measure power. Find the reading of each wattmeter.
4 M
4(c) An alternating current of frequency 50 Hz has a maximum value of 12 A. Write down instantaneous current eauation. Find the value of current after 2.77 ms. Also find time taken to reach 9.6 A for the first time.
5 M
4(d) Derive rectification efficiency and ripple factor of a full wave centre tapped rectifier.
4 M

5(a) Calculate the current through 5Ω resistor using Thevenin's theorem.
!mage.
8 M
5(b) For an RL circuit prove that average power over one complete cycle is Vrms Irms cosθ.
4 M
5(c) A 12 kVA, 400/200 V single phase 50Hz transformer has maximum efficiency of 95% at 85% of full load at unity power factor. Determine the efficiency at full load at 0.8 power factor lagging.
8 M

6(a) Find current through 9Ω resistor using superposition theorem.
!mage
7 M
6(b) A series RLC circuit has the following parameter values R=10Ω, L=0.01H, C=100μH. Compute the resonant frequency , Q factor of the circuit , band width, lower and upper cut off frequency.
7 M
6(c) Prove that the power and power factor in a balanced three phase circuit can be calculated form the reading of two watt meters. Draw relevant connection and phasor diagram.
6 M

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