STUPIDSID
Solve any one question from Q1 and Q2
1 (a)
Obtain the equation for coefficient of coupling between two coils placed on common magnetic field.
6 M
1 (b)
A water pump lifts 50 m3 of water per hour to a height of 20 m. The overall efficiency of water pump set is 0.60. Find monthly bill, when the pump is used 4 hours a day for a month of 30 days, at the rate of Rs. 5/kWh.
6 M
2 (a)
Explain the effect of temperature on resistance of:
(i) metal conductors
(ii) insulators
(iii) alloys.
(i) metal conductors
(ii) insulators
(iii) alloys.
6 M
2 (b)
A steel ring of mean diameter of 50 cm is wound with
500 turns on it. A flux density of 1 Tesla is produced in
the ring by mmf of 4000 AT/m. Calculate magnetising current. Also find the current when an air gap of 1 mm is cut in it, keeping B = 1 Tesla in the ring.
6 M
Solve any one question from Q3 and Q4
3 (a)
Obtain the expression for composite capacitor having 3-dielectric materials.
7 M
3 (b)
A 50 Hz sinusoidal voltage has rms value of 200 V. At
t = 0, the instantaneous value is positive and half of its maximum value. Write down the expression for voltage and sketch the wave form.
6 M
4 (a)
Derive an equation for average value of sinusoidal current in terms of its peak value.
6 M
4 (b)
A 40 kVA, 2200/220 V, 50 Hz, 1-ph transformer has an iron loss of 250 W. The resistances of low and high voltage windings are 0.005 Ω and 0.5 Ω respectively. Calculate efficiency at full load and load p.f. = 0.8 lagging.
7 M
Solve any one question from Q5 and Q6
5 (a)
Obtain the expression for power, if x = vm sin out is applied to R-L series circuit.
6 M
5 (b)
Three identical impedances each of 6 + j8 Ω are connected
in star across 3-ph, 400 V, 50 Hz a.c. supply. Calculate:
(i) line current
(ii) active power
(iii) reactive power.
(i) line current
(ii) active power
(iii) reactive power.
7 M
6 (a)
What is series resonance? Obtain the equation for resonant frequency.
6 M
6 (b)
Two circuits having impedances Z1 = 8 + j6 Ω and Z2 = 5 +j10 Ω are connected in parallel across 200 V, 50 Hz, 1-ph a.c. supply. Calculate:
(i) current drawn by each circuit
(ii) total current
(iii) p.f. of whole circuit.
(i) current drawn by each circuit
(ii) total current
(iii) p.f. of whole circuit.
7 M
Solve any one question from Q7 and Q8
7 (a)
Using simple series-parallel combination, find RBC for Fig 1.
6 M
7 (b)
Obtain the equations to convert A-connected resistances into equivalent star circuit.
6 M
8 (a)
State the Thevenin's theorem and explain the steps to find Rth, Vth and Ith.
6 M
8 (b)
Using Mesh/Loop analysis, calculate current flowing through RBC for Fig 2.
6 M
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