BACHELOR OF COMPUTER APPLICATIONS (Part-I) EXAMINATION

(Faculty of Science) (Three – Year Scheme of 10+2+3 Pattern)

PAPER - 111 ELECTRICAL CIRCUIT AND CIRCUIT ANALYSIS

OBJECTIVE PART- I

Year - 2011 �Time allowed : One Hour Maximum Marks : 20 The question paper contains 40 multiple choice questions with four choices and student will have to pick the correct one (each carrying ½ mark).��1. The force of attraction or repulsion between charges follows: (a) Square law of distance (b) Inverse square law of distance (c) Both (a) and (b) (d) None of (a) and (b) ( ) 2. When the distance between two equal charges is decreased to half and their magnitude of charges also decreased to half, the force between them: (a) Remains unchanged (b) Reduces to half (c) Becomes half (d) None of the above ( ) 3. Electric field intensity due to a point charge follows: (a) Falls inversely proportional to the distance (b) Falls inversely proportional to the square root of the distance (c) It does not change with distance (d) Falls inversely proportional to the square of the distance ( ) 4. One volt potential difference is equivalent to:

(a) 1 Newton/coulomb (b) 1 erg/Coulomb (c) 1 Joule/coulomb (d) 1 Coulomb/Joule ( ) 5. In a charged capacitor, the energy appears as: (a) Magnetic energy (b) Electromagnetic energy (c) Electrostatic energy (d) Mechanical energy ( ) 6. Unit of capacitance is: (a) Coulomb (b) Volt (c) Henry (d) Farad ( ) 7. What is the potential due to a point charge ‘q’ at a distance ‘r’ from it:

(a) (b)

(c) (d) ( )

8. Energy stores in an electric field is given by:

(a) (b)

(c) (d) ( )

9. Three resistance of 500 ohm, 5000 0hm and 50 ohm are connected in series across a 555 volt main. What is the current flowing through them? (a) 1 A (b) 100 mA (c) 10 mA (d) 10 A ( ) 10. If two capacitances of 100 f and 150 f are connected in parallel, what will be their total capacitance? (a) 60 f (b) 250 f (c) 15 f (d) None of the above ( ) 11. Capacitive time constant is given by:

(a) RC (b)

(c) (d) ( )

12. The energy stores in a magnetic field is given by:

(a) (b)

(c) (d) LI2 ( )

13. Two resistances of 0.275 ohm and 0.778 ohm are connected in parallel. The total resistance shall be: (a) More than 0.275 ohm (b) Less than 0.275 ohm (c) Equal to 1.053 ohm (d) More than 0.778 ohm ( ) 14. The ‘electron-volt’ is a unit of: (a) momentum (b) potential difference

(c) electric current (d) energy of the electron ( ) 15. In a series resonant circuit, the current at resonance is: (a) maximum (b) minimum (c) zero (d) none of the above ( )

16. The resonant frequency of a circuit is given by:

(a) (b)

(c) (d) ( )

17. Rejector circuits are: (a) Parallel resonant circuits (b) Series resonant circuits (c) Both parallel and series resonant circuits (d) None of the above ( ) 18. The effective capacitance is reduced when capacitor are connected in: (a) Series (b) Parallel (c) Series Parallel Combination (d) None of the above ( ) 19. Ohm’s law does not apply to: (a) A.C. circuits (b) Conductors (c) Semi-conductor (d) Conductor when there is change in temperature ( ) 20. The effective capacitance between ‘A’ and ‘B’ is:

2µf2µf

2µf

A B

(a) 1 f (b) f

(c) f (d) 3 f ( )

21. The resistivity of a wire depends on: (a) Its length (b) Its cross section (c) Both (a) and (b) (d) On the material ( ) 22. The resistant between A and B of the circuit given below:

A B

Ω3 Ω3

Ω3 Ω3 (a) 12 Ω (b) 6 Ω (c) 3 Ω (d) 1 Ω ( ) 23. Magnetic induction due to a solenoid of length ‘L’ radius R, no. 7 turns N and current I is: (a) (b)

(c) (d) ( )

24. The unit of magnetic flux density is: (a) Weber/m (b) Weber (c) Weber/m2 (d) amp/m ( ) 25. The commercial unit of electrical energy is: (a) Joules (b) Watt (c) Kilowatt (d) Kilowatt hour ( ) 26. The function of d.c. motor is: (a) to convert energy to electrical energy (b) to convert electrical energy to mechanical energy (c) to convert electrical energy to magnetic energy (d) to convert magnetic energy of electrical energy ( ) 27. Lenz’s law is based on the conservation of: (a) Charge (b) Momentum

(c) Energy (d) Mass ( ) 28. The permeability of a material is:

(a) (b)

(c) (d) ( )

29. Copper is: (a) Paramagnetic (b) Ferromagnetic (c) Diamagnetic (d) non-magnetic ( ) 30. The example of ferromagnetic material is: (a) Aluminum (b) Nickel (c) Mercury (d) Manganese ( ) 31. A generator is based on the principle of: (a) Salf-inductance (b) Electrical induction (c) Electromagnetic induction (d) Mutual induction ( ) 32. The impedance of 200 mH induction coil at 1 KHz will be: (a) 200 ohms (b) 1257 ohms (c) 628 ohms (d) 12.57.105 ohms ( ) 33. Norton theorem is converse of: (a) Thevenin’s theorem (b) Superposition theorem (c) Reciprocity theorem (d) Maximum power transfer theorem ( ) 34. A four terminal network has: (a) Two ports (b) One port (c) Three ports (d) No port ( ) 35. Transformer ratio is 10. It means that:

(a) NS = 10 NP (b) Ns =

(c) VS = (d) IS = 10 IP ( )

36. A fuse wire has: (a) a low melting point (b) a low resistance (c) a small radium (d) negligible mechanical strength ( )

37. Maximum power which a generator of e.m.f E and internal impedance Rg can supply to a load is:

(a) (b)

(c) (d) ( )

38. A cell of internal resistance 2 Ω is connected to a variable external resistance R. The power in the external resistance will be maximum when R is equal to: (a) Zero (b) 1 ohm (c) 2 ohms (d) 6 ohms ( ) 39. An electric field can deflect: (a) X-rays (b) Neutrons (c) particles (d) rays ( ) 40. Earthing is used:

(a) As a neutral line (b) to save power (c) to reduce voltage fluctuation (d) as a safety measure ( ) Answer Key 1. ( ) 2. ( ) 3. ( ) 4. ( ) 5. ( ) 6. ( ) 7. ( ) 8. ( ) 9. ( ) 10. ( )

11. ( ) 12. ( ) 13. ( ) 14. ( ) 15. ( ) 16. ( ) 17. ( ) 18. ( ) 19. ( ) 20. ( )

21. ( ) 22. ( ) 23. ( ) 24. ( ) 25. ( ) 26. ( ) 27. ( ) 28. ( ) 29. ( ) 30. ( )

31. ( ) 32. ( ) 33. ( ) 34. ( ) 35. ( ) 36. ( ) 37. ( ) 38. ( ) 39. ( ) 40. ( )

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DESCRIPTIVE PART - II

Year 2011

Time allowed : 2 Hours Maximum Marks : 30 Attempt any four questions out of the six. All questions carry 7½ marks each.

Q.1 (a) What is Coulomb’s law? Define electric lines of force.

(b) What is difference between electric potential and potential difference?

(c) Calculate the capacitance of series and parallel combination of three capacitors.

Q.2 (a) What is a condenser? Explain its principle.

(b) Explain the use of condenser in electronic circuits. What is the gang condenser?

(c) State Ohm’s law and define resistance of a conductor. On what factors and how

does the resistance of a conductor depend?

Q.3 (a) State Kirchhoff’s laws and explain their application with the help of examples.

(b) Explain the series and parallel combination of resistances.

(c) What is time constant? Show graphically the dependence of charging and

discharging process of time constant.

Q.4 (a) State Biot-Savarts Law. Using this obtain expression for magnetic induction at a

point on the axis of a current carrying coil.

(b) Calculate the magnetic induction inside a solenoid of 50 cm long and number of

twins per unit length is 100, the current flowing in solenoid is 10 amp.

Q.5 Write short notes on the following:

(a) Series resonance L-C-R circuit.

(b) DC Motor.

Q. 6 (a) State and prove Thevenin’s theorem. Find Norton’s equivalent of the Thevenin’s

equivalent circuit.

(d) Write the statement of reciprocity and maximum power transfer theorem.

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ELECTRICAL CIRCUIT AND CIRCUIT ANALYSIS PAPER - 111

OBJECTIVE PART- I

Year - 2010 �Time allowed : One Hour Maximum Marks : 20 The question paper contains 40 multiple choice questions with four choices and student will have to pick the correct one (each carrying ½ mark). 1. A kilowatt hour is a unit of :

(a) Energy (b) Power (c) Electric Charge (d) Electric Current ( )

2. Dielectric constant is a : (a) Dimensionless Quantity (b) Universal Constant (c) Conversion Quantity (d) None of the above ( )

3. A charge Q is situated at the centre of a cube. the electric flux emerging out through its surface will be :

(a) (b) 0

2Q∈

(c) 0

8Q∈

(d) 0

6Q∈

( )

4. If dielectric medium of constant K is filled between the plates of a capacitor, then its capacity increases:

(a) times (b) k times

(b) K2 times (d) ( )

5. The Unit of electric field intensity is: (a) Newton/meter (b) Coulomb/Newton (c) Newton/Coulomb (d) Joule/Newton ( ) 6. The value of 1 electron volt is: (a) 1.6 X 10–19J (b) 1.6 X 1019J (c) 3.2 X 10–19J (d) 1.6 X 10–20 J ( ) 7. The energy stored in an capacitor is in the form of: (a) Kinetic energy (b) Potential energy (c) Magnetic energy (d) Elastic energy ( ) 8. The capacitance of a capacitor does not depend upon:

(a) Shape of plates (b) Size of Plates (c) Charge on plates (d) Separation between plates ( ) 9. A 4 µ F capacitor is charged to 400 V. The energy stored in it will be: (a) 0.16 J (b) 0.32 J (c) 0.64 J (d) 1.28 J ( ) 10. Four capacitor each of capacity 3 Farad are connected in series. The resultant capacity will be: (a) (b)

(c) (d) ( ) 11. A parallel plate capacitor is given a charge Q. If the area of plates is doubled, its capacity will be: (a) Halved (b) Doubled (c) Zero (d) Unchanged ( ) 12. The specific resistance of a wire depends upon: (a) Its length (b) Its cross-section area (c) Its dimensions (d) Its material ( ) 13. When two resistances are connected in series, they have: (a) Same voltage (b) Same resistance (c) Same current (d) Different current ( ) 14. Unit of resistivity is: (a) ohm/meter (b) ohm/meter2

(c) ohm-meter (d) ohm-meter2 ( ) 15. Kirchhoff's first low is related to the law of: (a) Conservation of energy (b) Conservation of charge (c) Conservation of mass (d) Conservation of angular momentum ( ) 16. The conductivity of superconductor is : (a) Infinite (b) Very large (c) Very small (d) Zero ( ) 17. The current i in the given circuit is:

30 Ω 30 Ω

30 Ω

+-

2V

(a) (b)

(c) (d) ( )

18. The example of non-ohmic resistance is: (a) Copper wire (b) Carbon wire (c) Diobe (d) Tungsten wire ( ) 19. The path of a charged particle moving in a direction perpendicular to the magnetic field is: (a) Elliptical (b) Rectangular (c) Circular (d) Helical ( ) 20. The magnetic induction at the centre of a circular current carrying coil of redius 'r" is: (a) µOni (b) 2µOni 2a a (c) µOni (d) Zero ( )

a

21. The rays which remain unperfected in a magnetic field are:

(a) (b) (c) (d) Positive rays ( ) 22. The cause of diamagnetism is: (a) Orbital motion of electrons (b) Spin motion of electrons (c) Paired electrons (d) None of the above ( ) 23. A bar magnet of magnetic moment 'M' is cut into two equal parts. The magnetic moment of either of part will be: (a) 2 M (b)

(c) (d) Zero ( )

24. The coefficient of self induction of a coil is given by: e

(a) L = (b) L = –

(c) L = (d) L = – ( )

25. The peak value of a.c. is 4 Ampere the root mean square value of current in the circuit is: (a) 4 Ampere (b) Ampere

(c) Ampere (d) 8 Ampere ( )

26. The average value of alternating current over one complete cycle is: (a) Io (b)

(c) (d) Zero ( )

27. In an deal circuit, the power is consumed in: (a) R (b) C (c) L (d) L and C ( )

28. The impedance of an R- L series circuit is given by:

(a) R + XL (b)

(c) R2 + (d) None of the above ( )

29. In LCR circuit, the power factor to be 1, the condition is: (a) R=O (b)

(c) (d)

30. When frequency of an parallel LCR circuit increase, the impedance Z: (a) First decreases and then increase (b) First increase and then decreases (c) Increases uniformly (d) Decreases uniformly ( ) 31. The efficiency of a .d. c motor is:

(a) (b) (c) (d) None of the above ( ) 32. To convert mechanical energy into electrical energy, we can use:

(a) Dynamo (b) Motor (c) Transformer (d) Galvanometer ( ) 33. Transformer is based on the principle of: (a) Self induction (b) Mutual induction (c) Electromagnetic (d) Electrical induction ( ) 34. A galvanometer can be changed into ammeter by: (a) Adding a low resistance in series with it (b) Adding a low resistances in parallel with it (c) Adding a high resistance in series with it (d) Adding a high resistance in parallel with it ( ) 35. For an ideal voltmeter, the resistance should be: (a) Zero (b) Infinite (c) Very high (d) None of the above ( ) 36. An active element in a circuit is one which: (a) Receives energy (b) Supplies energy (c) Both (a) and (d) (d) None of the above ( ) 37. The maximum power transferred to the load P-L is: (a) (b)

(c) (d) 38. Norton theorem is converse of: (a) The venin's theorem (b) Superposition theorem (b) Reciprocity theorem (d) Maximum power transfer theorem ( ) 39. A four terminal network has: (a) Two ports (b) One port (c) Three ports (d) No port ( ) 40. The permeability of a material is: (a) µ (b) µ

(c) µ (d) µ ( )

Answer Key

1. (a) 2. (a) 3. (a) 4. (b) 5. (c) 6. (a) 7. (b) 8. (c) 9. (b) 10. (a)

11. (b) 12. (d) 13. (c) 14. (c) 15. (b) 16. (a) 17. (c) 18. (c) 19. (c) 20. (a)

21. (c) 22. (c) 23. (b) 24. (a) 25. (c) 26. (d) 27. (a) 28. (b) 29. (c) 30. (b)

31. (a) 32. (a) 33. (b) 34. (b) 35. (b) 36. (b) 37. (c) 38. (a) 39. (a) 40. (b)

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DESCRIPTIVE PART - II

Year 2010

Time allowed : 2 Hours Maximum Marks : 30 Attempt any four questions out of the six. All questions carry 7½ marks each. Q.1 (a) Define electric field intensity. Derive an expression for electric field due to a

point charge.

(b) What do you mean by the quantization of charge ?

(c) Find out the capacitance of series and parallel combination of three capacitors.

Q.2 (a) Derive an expression for the capacitance of a parallel plate capacitor.

(b) State Ohm's law and define resistance of conductor.

(c) An electric bulb of 484 Ω supplies light when connected to 220 V supply.

Calculate electric power of bulb and current flowing through it.

Q.3 (a) What is drift velocity? Write its relation with current.

(b) Discuss the effect of rise in temperature on the electrical conductivity of (i)

Semiconductor (ii) Insulator.

(c) Calculate the equivalent resistance between A and B in the following circuit.

A B

Q.4 (a) Explain Biot-Svart's law with diagram.

(b) A current is flowing through a long straight wire. Find out the expression for

magnetic field

(c) State and explain Lenz's law.

Q.5 (a) Define Z-factor and bandwidth for a series resonance L-C-R circuit.

(b) Draw parallel L-C-R resonant circuit. How is it differ from a series resonant L-CR

circuit?

(c) The equation of an a.c. current is given by i=4 sin . Find out the time

period of current.

Q.6 (a) Explain construction and working of a.b.c. motor.

(b) State and prove Thevenin's theorem.

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