Thursday, February 24, 2011

VERY IMPORTANT ELECTRICAL ENGINEERING OBJECTIVE TYPE QUESTIONS

    a. electrons 
    b. protons
    c. electrons and ions
    d. charged particles.
ans: a.

2. An electric current is the
    a. random movement of electrons in a conductor
    b. movement of free electrons predominantly in one direction
    c. pressure difference between the poles
    d. the power that causes drift of electrons
ans: b.


3. In gases the flow of current is due to 
    a. electrons only 
    b. positive and negative ions 
    c. electrons and positive ions
    d. electrons, positive ions and negative ions
ans: d.


4. The minimum requirement for causing flow of current are 
    a. a voltage source, a resistor and a switch 
    b. a voltage source and conductor
    c. a power source and bulb
    d. a voltage source, a conductor, an ammeter and a switch 
ans: b.


5.The draft velocity of electrons is 
    a. larger than speed of light
    b. almost equal to speed of light 
    c. equal to speed or light 
    d. very small in comparison to speed of light 
ans: d.

6.The resistance of the filament of a bulb is higher than the cold resistance because the temperature  coefficient of the filament is 
    a. Negative
    b. Infinite
    c. Zero
    d.  Positive
 ans:d.

7. The temperature coefficient of resistance of an insulator is 
    a. positive and independent of temperature
    b. negative and independent of temperature
    c. negative and dependent of temperature
    d. positive and dependent of temperature.
ans:c.


8. A network has 4 nodes and 3 independent loops. what is the number of branches in the network?
    a. 5
    b. 6
    c. 7
    d. 8.
ans:b.


9. If there are b branches and n nodes the number of equations will be 
   a. n-1
   b. b
   c. b-n
   d. b-n+1
ans:d.


10. An electric circuit with 10 branches and 7 nodes will have 
   a. 3 loop equations
   b. 4 loop equations
   c. 7 loop equations 
   d. 10 loop equations
ans:b.

11. A network has 10 nodes and 17 branches. The number of different node pair voltage would be 
    a. 7
    b. 9 
    c. 45 
    d. 10 
ans:b.


12. If the number of branches in a network is B the number of nodes is N and the number of     dependent loops is L then the number of independent node equations will be 
    a. N-L-1
    b. B-1
    c. B-N 
    d. N-1
ans:d.


13. The graph of an electrical network has N nodes and B branches. The number of links L , with respect to the choice of tree, is  given by 
    a. B-N+1
    b. B+N
    c. N-B+1
    d. N-2B-1.
ans:a.


14. The number of possible ordered trees with 3 nodes A,B,C is 
    a. 6
    b. 8
    c. 10 
    d. 12
ans:d.

15. What is the number of chords of a connected graph G of n vertices and e edges?
    a. n(n-1)
    b. n-1
    c. e-n-1
    d. e-n+1.
ans:d.


16. Ideal voltage source have 
    a. zero internal resistance 
    b. infinite internal resistance
    c. low value of current
    d. large value of emf
ans:a.


17. Ideal current source have 
    a. zero internal resistance 
    b. infinite internal resistance
    c. low value of voltage
    d. large value of current.
ans:b.


18. A parctical current source is represented by 
    a. a resistance in series with an ideal current source
    b. a resistance in parallel with an ideal current source
    c. a resistance in parallel with an ideal voltage source
    d. none of the above
ans:b.


19. A dependent source 
   a. may be a current source or a voltage source
   b. is always a voltage source 
   c. is always a current source
   d. neither a current source nor a voltage source
ans:a.


20.To neglect a voltage source, the terminals across the source are 
    a. open-circuited 
    b. short-circuited
    c. replaced by some resistance
    d. replaced by inductor
ans:b.


21. Kirchoff's laws are valid for 
    a. linear circuits only 
    b. passive time invariant circuits 
    c. non linear circuits only 
    d. both linear and non- linear circuits
ans:d.


22. Kirchoff's voltage law is concerned with 
    a. IR drop
    b. battery emf
    c. junction voltage
    d. both a and b.
ans:d.


23. Superposition theorem is not applicable for 
   a. voltage calculations 
   b. bilateral elements
   c. power calculations
   d. passive elements
ans:c.


24. which of the following theorems applicable for both linear and non-linear circuits?
   a. superposition 
   b. Thevenin's 
   c. Norton's 
   d. none of these.
ans.d.


25. Superposition theorem is not applicable for 
    a. voltage calculations
    b. bilateral elements
    c. power calculations
    d. passive elements
ans:c.


26. Maxwell's loop current method of solving electrical networks 
    a. uses branch currents
    b. utilises kirchoff's voltage law
    c. is confirmed to single-loop circuits
    d. is a network reduction method.
ans:b.


27. Nodal analysis is based on 
    a. KCL
    b. KVL
    c. both
    d. law of conservation of energy .
ans:a.


28. In nodal analysis , if there are N nodes in the circuit, then how many equations will b written to solve the network?
    a. N-1
    b. N+1
    c. N
    d. N-2.
ans:a.


29. Point out the wrong statement. In the node voltage technique of solving networks , choice of a reference nodes does not 
    a. affect the operation of a circuit
    b. change the voltage across any element
    c. alter the pd between any pair of nodes 
    d. affect the voltages of various nodes.
ans:d.


30. In a balanced Wheatstone bridge, if the positions of detector and source are interchanged , the bridge will still remain balanced. This inference can be drawn from
    a. reciprocity theorem
    b. duality theorem
    c. compensation theorem
    d. equivalence theorem
ans. a.


31. which of the following theorems can be applied to any network- linear or non-linear , active or passive , time-variant or time-invariant?
    a. Thevenin theorem
    b. Norton theorem
    c. Tellegen theorem
    d. superposition theorem
ans:c.


32. A passive 2-port network is in a steady state. compared to its input, the steady state output can never offer
    a. higher voltage
    b. lower impedence
    c. greater power
    d. better regulation
ans.c.


33. Pole of a network is a frequency at which 
    a. network function becomes zero
    b. network function becomes infinite
    c. network function becomes unity
    d. none of these
ans.b.


34. A pole of driving point admittance function implies 
   a. zero current for a finite value of driving voltage
   b. zero voltage for a finite value of driving current
   c. an open circuit condition 
   d. none of a, b and c mentioned in the equation
ans:b.


35. The lowest and the highest critical frequencies of an R-L driving point impedance are, respectively 
    a. a zero, a pole
    b. a pole , a pole 
    c. a zero, a zero 
    d. a pole , a zero
ans:a.


36. The first and last critical frequencies of a driving point impedance function of a passive network having two kinds of elements , are a pole and a zero respectively. The above property will be satisfied by 
    a. RL network only
    b. RC network only
    c. LC network only
    d. RC as well as RL networks
ans:b.


37. Standard cell
 a. will have precise and accurate constant voltage when current drawn from it is few    microamperes only.
   b. will have precise and accurate constant voltage when few milliamperes are drawn from it.
   c. will continue to have constant voltage irrespective of loading conditions.
   d. can supply voltages upto 10V.
ans:a.


38. The energy capacity of a storage battery is rated in 
    a. kWh
    b. kW
    c. ampere hours
    d. joules.
ans:c.


39. Coulomb's law for the force between electric charges most closely resembles with 
   a. Newton's law of motion
   b. law of conversion of energy
   c. gauss's theorem
   d. Newton's law of gravitation
ans:d.

40. Which one of the following statements does not state that electrostatic field is conservative?
    a. The curl of E is identically zero.
    b. The potential difference between two points is zero
    c. The electrostatic field is a gradient of a scalar potential
    d. The work done in a closed inside the field is zero.
ans:b.


41. Across the surface of a charged conductor , the electric 
    a. field is continous
    b. potential is discontinuous
    c. field is discontinuous 
    d. none of the above
ans:c.

42. Unit of electric intensity is 
    a. joules/coulomb
    b. newton/coulomb
    c.volt/meter
    d. both b and c.
ans:d.


43. What is the value of total electric flux coming out of closed surface?
    a. zero
    b. equal to volume charge density.
    c. equal to total charge enclosed by the surface
    d. equal to the surface charge density
ans:c.

44. Inside a hollow conducting sphere
    a. electric field is zero
    b. electric field is a non-zero constant 
    c. electric field changes with the magnitude of the charge given to the conductor 
    d. electric field changes with distance from the centre of the sphere.
ans:a.


45. The tangential component of the electric field on a perfect conductor will be 
    a. infinite
    b. zero
    c. same as the normals field component and 90' out of phase
    d. same as the normal component but 180' out of phase.
ans:b.


46. In a charge-free space , the poisson's equation results in which one of the following ?
    a.continuity equation
    b. maxwell's equation
    c. laplace equation
    d. none of the above.
ans:c.


47. If E=0 at all points on a closed surface,
   1. the electric flux through the surface is zero
   2. the total charge enclosed by the surface is zero
   3. the charge resides on the surface
    a. 1 and 2 only are correct 
    b. 2 and 3 are only correct
    c. 1 and 3 are only correct 
    d. 1,2 and 3 are correct.
ans:d


48. Which one of the following is the correct statement?
 equipotential lines and field lines 
    a. are parallel 
    b. are anti-parallel
    c. are orthogonal
    d. bear no definite realtionship 
ans:c.


49. Equipotential surfaces about a pair of equal and opposite linear charges exist in what form ?
    a. concentric spheres
    b. concentric cylinders
    c. non-concentric cylinders
    d. planes 
ans:d.


50. Equipotential surfaces about a point charge are in which one of the following forms ?
    a. spheres
    b. planes
    c. cylinders
    d. cubes
ans:a.






    
   



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