D 1108

Reg No.: Name:

FIRST SEMESTER B.TECH DEGREE EXAMINATION(S), MAY 2019

Course Code: BE101-03
Course Name: INTRODUCTION TO ELECTRICAL ENGINEERING

Max. Marks: 100 Duration: 3 Hours
PART A
Answer all questions, each carries4 marks. Marks
1 Deduce an expression for the energy stored in a magnetic field? (4)
2 A coil of 160 turns is linked with a flux of 0.02 Wb when carrying 8 current of (4)

12A. Calculate the inductance of the coil. If the current is uniformly reversed in

0.02 s, calculate the induced emf.
3 State and explain Kirchhoff’s voltage and current laws. (4)
4 Distinguish between self and mutual inductances. Derive an expression for the (4)

self inductance of a coil.

5 Express 1(1) = 20 sin(628¢ -30 ) in polar and rectangular forms. (4)

6 Prove that the power consumed by a purely vapacitive ac circuit is zero. (4)

7 Distinguish between (i) apparent power, (ii) active power, and (iii) reactive (4)
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8 Prove that average power in an ac circuit is VI ६050, where V is the RMS value (4)

of voltage, I 15 the RMS value of current and ६050 is the power factor.

9 Calculate the line currents, power factor and power consumed in a three phase (4)
star connected load consisting of three equal impedances of (20+j10) Q
connected across a three phase source of 400V, 50Hz.

10 Write any four advantages of three phase systems over single-phase systems. (4)
PART B
Answer any four full questions, each carries10 marks.
11 8) State and explain Faraday’s laws of electromagnetic induction. (4)

0) 4 6011 of 800 turns is wound on a ring of silicon steel, having mean diameter of 9 (6)
cm and relative permeability of 1100. Its cross sectional area is 12cm?. When a
current of 6 A flows through the coil, find

i. Flux in the core
ii. Inductance of the coil
iii. Induced emf if the flux falls to zero in 20ms.

12 Use Mesh analysis to determine currents 11, 12, 13 and current through the 3೧ (10)

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