1. Select the correct answer from the given four alternatives for the following multiple choice objective type questions:

(a) The ratio of clearance volume to swept volume is called
Cut-off ratio

(ii) Expansion ratio

(iii) Clearance ratio
None of the above

(b) The difference between Cp and Cv is equal to R

(ii) 2R

(iii) R/2
depends upon the atomicity of gas molecules W P1V1 loge (V2 V1) when P1,V1 and p2, V2 are the initial and final pressures and volume respectively. W is the work done. The above equation is true for
Isothermal process

(ii) Adiabatic process

(iii) Polytropic process
Constant pressure process
The ratio of clearance volume to total volume is called Cut-off ratio

(ii) Expansion ratio

(iii) Compression ratio
None of the above In a vapour compression system, the lowest temperature during the cycle occurs after Compression

(ii) Condensation

(iii) Expansion·
Evaporation


(f) In a four-stroke cycle engine, all the four operations are completed in
revolutions of crank shaft.
Which of the following refrigerants IS highly toxic and inflammable? Ammonia

(ii) Carbon dioxide

(iii) Sulphur dioxide
Freon-12 The current in the arm CD of the circuit will be <img src='./qimages/10725-1h.jpg'> i1 i2
i2 i3

(iii) i1 i3
i1 -i2 i3


(i) The filament of an electric lamp draws a current of 0·4 amperes, which lights for 3 hours. The amount of charge that flows in the circuit is
1·2 Coulomb

(ii) 4·32 x 10^3 Coulomb

(iii) 72·0 Coulomb

(iv) 4·32 x 10^6 Coulomb The device used for producing current is called Generator

(ii) Voltmeter

(iii) Ammeter
Galvanometer Lenz's law is a consequence of the law of conservation of charge

(ii) mass

(iii) momentum
energy When a capacitor is connected to a battery
an alternating current flows in the circuit

(ii) no current flows at all

(iii) a current flows for some time and finally it decreases to zero
current keeps on increasing and reaches maximum after some time A bird sitting on a high power line gets killed instantly

(ii) gets a mild shock

(iii) is not affected practically
gets a fatal shock. Which of the following quantities remains constant in a step-down transformer? Current

(ii) Voltage

(iii) Power
None of the above

2. Attempt any two of the following: Explain the following terms as applied to I.C. engine:
Bore

(ii) Stroke

(iii) TDC
BDO Clearance volume

(vi) Swept volume

(vii) Compression ratio Discuss the working of a two-stroke petrol engine with the help of neat sketches. An IC engine rotates at 2400 r.p.m. The four-stroke engine has a cylinder bore diameter of 100 mm and crank radius of 100 mm. From indicator diagram, the mean effective pressure is found as 100 kPa. If the mechanical efficiency is find the brake power of the engine.

3. Attempt any two of the following: Describe the vapour absorption refrigeration system with a neat sketch. What is lift How do you classify them? Describe anyone in brief. A Carnot cycle machine operates between the temperature limits of T1= 30°C and T2 Determine the COP when it operates as a refrigeration machine, and

(ii) a heat pump.

4. Attempt any two of the following: In the circuit shown in the following figure, determine the current flowing through the 12 ohm resistance.
<img src='./qimages/10725-4a.jpg'> Calculate the permeability of a steel sheet at a magnetic field strength of 250 AT/m when the flux density is 0·8 T.
When the element combination in Figure is connected to a 200 400 Hz supply, what would be the current drawn? What would be the voltage across the resistance and capacitance?

<br><br> <img src='./qimages/10725-4c.jpg'>

5. Attempt any two of the following:

(a) A 25 kVA transformer has 500 turns on primary and 50 turns on the secondary winding. The primary is connected to a 3300 50 Hz supply. Find the full load primary and secondary currents, the secondary emf and the maximum flux in the core. A 200 volts D.C. series motor runs on 500 r.p.m, when taking a current of 25 amperes. The resistance of armature is 0·5 ohms and that of the field is 0·3 ohms. If the current remains constant, calculate the necessary additional resistance in series with armature to reduce the speed to 250r.p.m. A long shunt compound generator supplies a load current of 50 amperes at 220 volts. Shunt field resistance is 110 ohms. Series field resistance is 0·01 ohm and armature resistance is 0·02 ohm. Find the emf generated and power developed in the armature. Take contact drop per brush as 1·5 volts.