CODE NO:- K-72

[Time: Two Hours]

[Max. Marks:40]

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

N.B i) Q .no. 1 are compulsory.

ii) Attempt any two questions from the remaining questions.

iii) Assume suitable data, if necessary.

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

a) State the effect of temperature on

i) Carbon ii) Copper

b) Define Temperature Coefficient of resistance.

c) State Thevenin’s Theorem.

d) Define time constant of RC circuit

e) Draw the curve for capacitor voltage during discharging & define time constant.

f) Define mutual Inductance.

g) Define MMF, magnetic flux & reluctance

h) What is eddy current loss?

Q. 2 a) If are temperature coefficients of resistance at t^{0}_{1}C & t^{0}_{2 }C respectively ,prove that** [05] **

\[ \frac{1}{\alpha _{1}}-\frac{1}{\alpha _{2}}=(t_{2}-t_{1}) \]

b) State and explain with neat diagram the concept of Mutual Inductance **[05]**

c) A 200 V dc supply is suddenly applied to a series combination of 5*μf* capacitor and 1MΩ resistor. Calculate **[05]**

1) Time taken by capacitor to rise it’s voltage up to150V.

2) The current through and P.D. across the capacitor 5 sec after it is connected to

supply.

Q. 3 a) State and explain superposition theorem. **[05]**

b)

Find current through 8Ω resistance using loop analysis. **[05]**

c)

Find RL such that maximum power transferred to it. Also find maximum power

transferred. **[05]**

Q. 4 a)

Find current through 3Ω resistance using Nodal Analysis. **[05]**

b)

Using Thevenin’s Theorem find the current through 4Ω resistor. **[05]**

c) State and explain maximum power transfer theorem. **[05]**

Q. 5 a) Explain the phenomenon of hysteresis loss & eddy current loss. **[05]**

b) Explain with neat diagram what is useful flux, leakage flux, fringing & its effect

on magnetic flux density. **[05]**

c) A mild steel ring has a mean circumference of 600 mm and uniform cross section

area of 200 mm2. Permeability of the ring is 1200 calculate **[05]**

1) MMF required to produce flux of 200uWb

2) If an air gap of 1mm is cut in the ring find flux produced in the gap if

MMF remains same.

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