Basic Electricals & Electronics Engg. - Dec 2014
First Year Engineering (Set A) (Semester 1)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
Solve any one question from Q1 & Q1 (e)
1 (a) Write the major difference between:
i) Ideal voltage source and practical voltage source
ii) Dependent and independent sources
(2 marks) 1 (b) Define :
i) Impedance and
ii) Phase sequence in a.c. circuit.(2 marks) 1 (c) Explain with units and
i) Real power
ii) Reactive power
iii) Apparent power in a.c. circuit.(3 marks) 1 (d) Derive the relation for conversion for star and delta connection.(7 marks) 1 (e) State Thevenin?s theorem. Determine the current through a 3Ω resistor branch in the circuit using Thevenin?s theorem. (14 marks)
Solve any one question from Q2 & Q2 (e)
2 (a) Define magnetic leakage and fringing.(2 marks)
2 (b) Give the reason of eddy current loss in transformer core.(2 marks)
2 (c) Define voltage regulation and efficiency of a transformer. Give the formula also.(3 marks)
2 (d) Draw the complete phasor diagram of a single phase transformer for an inductive load. Also write the notations used for all voltages and currents used in the phasor diagram.(7 marks)
2 (e) The results of tests performed on 1ϕ, 20 KVA, 2200/220 volt, 50 Hz. Transformer are as follows-
O.C. test : 220 V, 4.2 A, 148 W
S.C. test : 86 V, 10.5 A, 360 W.
The regulation and efficiency at 0.8 p.f. lagging at full load.(14 marks)
Solve any one question from Q3 & Q3 (e)
3 (a) Write the necessity and material used for the following in a d.c. machine
ii) Brush(2 marks) 3 (b) Why synchronous machine is called as synchronous. Define synchronous speed.(2 marks) 3 (c) Classify self excited D.C. motor.(3 marks) 3 (d) Derive the e.m.f. equation of a 3 phase Induction Motor.(7 marks) 3 (e) Draw and explain the complete Torque-slip characteristics of 3 phase induction motor.(14 marks)
Solve any one question from Q4 & Q4 (e)
4 (a) State and explain De Morgan?s theorem.(2 marks) 4 (b) Simplify the Boolean function Z = AB + AC + BC and therefore design the logic circuit using AND or OR logic gates.(2 marks) 4 (c) Explain half adder and full adder with truth table.(3 marks) 4 (d) Explain number systems used in digital electronics.(7 marks) 4 (e) Explain in detail J-K flip flop.(14 marks)
Solve any one question from Q5 & Q5 (e)
5 (a) Define ideal diode and practical diode.(2 marks) 5 (b) Differentiate between conductor, semiconductor and insulator with example.(2 marks) 5 (c) Draw and explain the V-I, characteristic of diode.(3 marks) 5 (d) Draw the connection diagram and explain the use and working of CE transistor configuration.(7 marks) 5 (e) Explain the working of BJT. Discuss DC biasing of BJT.(14 marks)