Punjab State Board of Technical Education and Industrial Training 2010-2nd Sem Diploma Electronics and Communication Basic Electrical Engineering in ECE - Question Paper

Basic Electrical Engineering

second examination /ECE/6125/2561/May'10
Duration: three Hrs. M. Marks: 75

Section- A

Q.1. Fill in the blanks : [Marks 15]
(a) The total resistance of 2 resistors of 20 ohm connected in parallel is ………… .

(b) A circuit having a few properties in either direction is called ………………. .

(c) An ideal current sources has …………….. internal resistances.

(d) The total number of magnetic lines of force set up in a magnetic circuit is called ………………….. .

(e) Absolute permeability of vacuum is …………….. .

(f) The cells in which chemical reaction is irreversible are called ……………… .

(g) The time taken by an alternating volume to complete 1 cycle is called ………….. .

(h) Form factor is the ratio of ………………… and ………………. .

(i) The ratio of actual power to apartment power is called ……………… .

(j) ……………… converts mechanical energy into electrical energy.

Section- B
Note: Attempt any 5 ques. : [Marks five X 6]

Q.2. (a) What is a series circuit ? Prove that in a series circuit the total resistance is equal to individual resistance.

(b) State and prove Nortan's theorem with example.

(c) Differentiate ranging from constant voltage source and constant current source.

(d) describe self and mutually induced e.m.f.

(e) Why batteries are connected in series and parallel combination?

(f) An alternating current is provided by expression i= 10sin314.t. compute :
(1) Maximum value of current
(2) Frequency
(3) Time period
(4) Intantaneous value of current of R-L-C series circuit.

Section- C

Note: Attempt any 3 questions: [Marks three X 10]

Q.3. explain in details the conversion of a data connection into equivalent star connection.

Q.4. (a) Prove that energy stored in a magnetic field is provided by W=1/2LI2, where L is the inductance of coil and I is the current flowing throw coil.

(b) 2 identical coils are connected in series. The total inductance is formed to be 24 H and eight H when the fluxes are addictive and subtractive respectively. compute mutual inductance ranging from 2 coils.

Q.5. explain constructions and working of nickel cadmium battery.

Q.6. (a) A 10 µF capacitor is connected across 230 V , 50 Hz supply, compute the capacitive reactance and current.

(b) What is the difference ranging from A.C and D.C ?

Q.7. explain with the help of phasor diagram, the effect of the alternating voltage applied to a R.L series circuit.

Earning:   Approval pending.