Elements of Electrical Engineering — Winter 2022

Choose the correct option from the given options Mark

07 1. The three resistors of resistance values 5Ω, 10 Ω, and 15 Ω are connected in parallel, what should be its equivalent resistance

Less than 5Ω (b) between 5Ω and 10Ω(c) between 10Ω and 15Ω(d) greater than 15 Ω 2. Kirchhoff’s voltage law is concerned with

IR drops (b) battery e. m. fs(c) junction voltages(d) both (a) &(b) 3. The resistance of each arm of delta connected network 6 Ω. The resistance of each arm of its equivalent star connected network is

6 Ω (b) 18 Ω (c) 2 Ω (d) 3 Ω 4. Acapacitor that stores a charge of 0.5 Cat 10V has capacitance of____farad.

5 (b) 0.05 (c) 20Ω (d) 5. The SI unit of electric field intensity is

N/m (b) V/m (c) N/C (d) either (b) or (c) 6. According to Faraday’s law of electromagnetic induction, an e. m .f. is induced in a conductor whenever it

lies in a magnetic field (b)cuts magnetic flux (c) moves parallel to the direction of the magnetic field(d) lies parallel to the magnetic flux 7. Acoil of 1000 turns is wound on a core. Acurrent of 1A flowing through the coil creates a core flux of 1 mWb. The energy stored in the magnetic field is

0.25 J(b)0.5J (c)1J (d)2J

07 1. The power factor of series R-L-Ccircuit under resonance condition is

0.8 lagging(b) unity (c)zero (d)0.8 leading 2. An AC current given by i=14.14 sin(wt +ᴨ/6) has an r. m. s. value of____A

7.07(b)1.96 (c)10 (d)14.14 3. The voltage applied across an R-Lseries circuit is equal to

arithmetic sum of Vand V (b) algebraic sum of Vand V (c) phasor sum R L R L of Vand V (d) sum of squares of Vand V R L R L 4. The minimum number of wattmeter(s) required to measure 3-phase, 3- wire balanced or unbalanced power is

4 (b)2 (c)3 (d)1 5. The rating of the battery is

Ah (b)kWh (c)W (d)hp 6. Fuse provides protection against

over load (b) short circuit (c)both (a)&(b) (d)lightning 7. Which of the following provides safety to human against electric shock

RELAY (b)FUSE (c)MCB (d)earthing

Write the statements of Kirchhoff’s law

Give difference between dependent and independent sources.

Find the current through the 2Ω resistor shown in figure 1 by using loop analysis. 4 V 2 V2 1 0 o h o m h m 1 0 o h m07 Figure 1

Write the laws of electrostatics

Derive the expression of energy stored in capacitor.

Explain the statically and dynamically induced e. m. f.

State Fleming’s and Lenz’s laws

Explain hysteresis loop.

Find the charges on capacitor C , Cand Cshown in figure 2.123 C 1 (2 μ F C ) C1 (3 (50 μ μ V F F ) )07 Figure

Explain form factor and peal factor for a sinusoidal waveform.

Explain real power, reactive power and apparent power in ac circuit.

Apure resistance of 50 ohms is in series with a pure capacitance of 100 microfarads. The series combination is connected across 100-V, 50Hz supply. Determine(a)the impedance(2)current(3)power factor(4)phase angle(5) voltage across the resistor(6)voltage across the capacitor.

What is the difference between balanced and unbalanced three phase load.

Write short note on CFL and LED lamps.

The power in a 3-phase circuit is measured by two wattcmeters. If the total power is 100KW and power factor is 0.66leading. What will be the reading of each wattmeter?

State the safety precautions to be taken in home to prevent electric shock.

Explain plate earthing with figure.

Explain ELCB in details.