FACULTY OF ENGINEERING AND TECHNOLOGY

First Year Examination – DEC – 2014

Element of Electrical Engineering(Revised)

CODE NO:- U-286

[Time: TWO Hours]

[Max. Marks: 40]

“Please check whether you have got the right question paper.”

N.B 1) Q.1 is compulsory.

2) Attempt any two questions from the remaining questions.

3) Assume suitable data if necessary.

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Q.1 Solve any five **[10]**

1) Draw the curve for capacitor voltage during charging & define time constant.

2) What is magnetic leakage & fringing?

3) Find current throl 5Ω resistance

4) State thevenin’s theorem.

5) State the effect of temperature on

a) Rubber

b) Gold

6) Define reluctivity & permeability

7) Prove ∝_{0}=R_{t}-R_{0}/R_{0}.t

8) Define self inductance

Q.2 a) Compare electric & magnetic circuits. **[05]**

b) Explain phenomenon of hysteresis and eddy current loss.**[05]**

c) A mild steel ring of cross section area and mean diameter 50cm is uniformly **[05]** wound with 200 turns and carries current 10A. permeability of mild steel is 1200. Find

1) MMF

2) Reluctance

3) Flux density

Q.3 a) With neat diagram explain the concept of self and mutually induced emf.**[05]**

b) If ∝_{0},∝_{1},∝_{2 }are temperature coefficient at 0^{0}_{C,}t^{0}_{1 }c,t^{0}_{2}_{ }c, respectively. Prove**[05]**

∝_{2}=∝_{1}/1+∝_{1}(t_{2}-t_{1})

c) A capacitor of 20 is charged through a pure resistance of 5MΩ with 200v dc supply. Find **[05]**

1) Time taken by capacitor to receive 90% of it’s final charge

2) Corresponding charging current.

Q.4 a) State and explain thevernin’s theorem. **[05]**

b) Find current though resistance RL=3 Ω using superposition theorem **[05]**

c) Find value of RL such that maximum power transferred to it. Also find maximum power dissipated. **[05]**

Q.5 a) State and explain super position theorem **[05]**

b) Find current through 3 Ω resistance using LOOP analysis. **[05]**

c) Using Nodal Analysis find the magnitude and direction of current I in the network. **[05]**

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