NMAT - Electrical Circuits 1000+ MCQ [Solved] PDF Download

1. A three-by-threea series-parallel matrix of resistorsa all having the same ohmic valuea would have a net resistance of
A. One-third the value of a single resistor
B. Three times the value of a single resistor
C. The same value as a single resistor
D. Nine times the value of a single resistor
Answer : C

2. A capacitor requires 12 C of charge to raise its potential of 3 V. What is the capacitance of the capacitor?
A. 36 F
B. 15 F
C. 0.25 F
D. 4 F
Answer : D

3. If two complex conjugates are addeda ___ components results.
A. In-phase
B. Quadrature
C. Complex
D. Outof-phase
Answer : A

4. In an inductive coila the rate of rise of current is maximum
A. Near the final maximum value of current
B. At midvalue of current
C. At half-power points
D. After one time constant
Answer : A

5. The charge in the capacitor is stored at the
A. Terminals
B. Plates
C. Dielectric
D. Air
Answer : B

6. Which is considered as the effect of a dielectric material?
A. Increasing capacitance
B. Decreasing capacitance
C. Reducing the working voltage
D. Increasing the distance between the plates
Answer : A

7. A capacitance of 6 ��F means
A. 6 pF
B. 6 nF
C. 6 fF
D. 6 aF
Answer : A

8. If the capacitance of mica capacitor is 5 times the capacitcitora then the relative permittivity of mica is
A.
B.
C.
D.
Answer : B

9. Form its definitiona the unit of electric fielda is the N/C and equivalent unit of is the
A. V(m)2
B. V(m)
C. V/m2
D. V/m
Answer : D

10. Which of the following is the statement of Ohm�s law?
A. Electric current is directly proportional to both voltage and resistance
B. Electric current varies directly as the voltage and inversely as the resistance
C. Electrical power is directly proportional to the resistance and inversely as the current squared
D. Electrical power is directly proportional to both voltage squared and the resistance
Answer : B

11. At parallel resonancea the currents flowing through L and C are
A. Infinite
B. Zero
C. Unequal
D. Equal
Answer : D

12. An inductive circuit of resistance 16.5 and inductance of 0.14 H takes a current of 25 ?. if the frequency is 50 Hza find the supply voltage.
A. 1501 V
B. 1174V
C. 1877V
D. 991 V
Answer : B

13. For a triangular and sawtooth waveform the rms voltage or current equals
A. 0.707times peak value
B. 0.577 times peak value
C. 0.577times average value
D. 0.707times rms value
Answer : B

14. Which factor does not affect resistance?
A. Length
B. Resistivity
C. Cross-sectional area
D. Mass
Answer : D

15. What is the peak factor for alternating current or voltage varying sinusiodally?
A.
B.
C.
D.
Answer : A

16. For a series circuita the higher the quality factor
A. The greater the bandwidth
B. The narrower the passband
C. The broader the resonance curve
D. The wider the passband
Answer : B

17. An ac series circuit is composed of a resistance of 20 a inductive reactance of 40 a and a capacitive reactance of 15 . If a current of 1 ampere is flowinga what is the applied voltage
A. 320 V
B. 32 V
C. 220 V
D. 22 V
Answer : B

18. A neon glow lamp used as a night light ionizes at approximately
A. 70 V
B. 80 V
C. 90 V
D. 100 V
Answer : A

19. The wavelength of an alternating waveform depends upon the ___ of the variation.
A. Period
B. Number
C. Frequency
D. Amplitude
Answer : C

20. The internal resistance of an ideal current source is
A. Infinite
B. Zero
C. Equal to the load resistance
D. To be determined
Answer : A

21. The reason why electrical appliances are connected in parallel.
A. It is a simple circuit
B. This makes the operation of appliances independent with each other
C. This results in reduced power consumption
D. All of the above
Answer : B

22. Transient period is considered over after
A.
B.
C.
D.
Answer : A

23. An electric circuit contains
A. Passive elements
B. Active elements
C. Both active and passive elements
D. Reactive elements
Answer : C

24. Which of the following capacitors has the highest cost per F?
A. Plastic
B. Air
C. Mica
D. Electrolytic
Answer : D

25. Which statement is true about a passive circuit?
A. A circuit with neither a source of current nor a source of potential difference
B. A circuit with a voltage source
C. A circuit with a current source
D. A circuit with only resistance as a load
Answer : A

26. A trimmer is a variable capacitor in which capacitance is varied by changing the
A. Number of plates
B. Dielectric
C. Distance between plates
D. Plate area
Answer : C

27. The electric field strength between capacitor plates has a unit
A. Volts per meter
B. Volts per mil
C. Amperes per meter
D. Amperes per mil
Answer : A

28. If a coil has a Q of 10a it means that
A. The energy stored in the magnetic field of the coil is 10 times the energy wasted in its resistance
B. The energy wasted in its resistance is 10 times the energy stored in the magnetic field of the coil
C. It is a low Q coil
D. It is a high Q coil
Answer : A

29. A rheostat is a form of
A. Variable resistor
B. Variable capacitor
C. Potentiometer
D. Thermocouple
Answer : A

30. An inductor carries 2 A dc. If its inductance is 100 Ha then what is its inductive reactance?
A. Zero
B. 1.3 k
C.
D.
Answer : A

31. What is the resonant frequency of a circuit when L of 3 microhenrys and C of 40 picofarads are in series?
A. 14.5 kHz
B. 145 MHz
C. 14.5 MHz
D. 145 kHz
Answer : C

32. A law which states that when a constant electromotive force is applied to a circuit consisting of a resistor and capacitor connected in seriesa the time taken for the potential on the plates of the capacitor to rise to any given fraction of its final value depends only on the product of capacitance and resistance.
A. Child�s law
B. CR law
C. Coulomb�s law
D. Debye T3 law
Answer : B

33. The distance between the capacitor plates increases two timesa then its capacitance
A. Increases two times
B. Increases four times
C. Decreases two times
D. Decreases four times
Answer : C

34. What is the specific resistance of a pure silicon?
A. 55 -mm
B. 55 -m
C. 55 -cm
D. 55 k -m
Answer : C

35. The power factor of a certain circuit in which the voltage lags behind the current is 80 %. To increase the power to 100 %a it is necessary to add ___ to the circuit.
A. Inductance
B. Capacitance
C. Resistance
D. Impedance
Answer : A

36. As applied to a series RLCcircuita bandwidth means
A. The frequency range for maximum power transfer
B. The difference between the highest and lowest frequencies of the oscillator
C. The separation of the half-power points
D. The frequency at which XL= XC
Answer : C

37. A factor that states how much the resistance changes for a change in temperature?
A. Resistivity
B. Specific resistance
C. Coefficient of temperature change
D. Temperature coefficient of resistance
Answer : D

38. The charging of a capacitor through a resistance obeys
A. Exponential law
B. Logarithmic law
C. Linear law
D. Square law
Answer : A

39. The reason why alternating current can induce voltage is
A. It has high peak value
B. It has a stronger magnetic field than direct current
C. It has a constant magnetic field
D. It has a varying magnetic field
Answer : D

40. In an ac circuit with inductive reactance ?, the
A. Phase angle of the circuit is always 45�
B. Voltage across the inductance must be 90� out o f-phase witht he applied voltage
C. Current through the inductance lags its induced voltage by 90�
D. Current through the inductance and voltage across it are180� outof-phase
Answer : C

41. What is the conductance of a circuit having three 10 resistors in parallel?
A. 0.3 S
B. 3.33 S
C. 0.33 S
D. 30 S
Answer : A

42. In a pure capacitancea
A. Current leads voltage by 90�
B. Current leads voltage by 180�
C. Current lags voltage by 90�
D. Current lags voltage by 180�
Answer : A

43. What is the form factor of a triangular wave?
A.
B.
C.
D.
Answer : A

44. What is the most common non-sinusoidal waveform?
A. Square wave
B. Triangular wave
C. Trapezoidal wave
D. Sawtooth wave
Answer : A

45. When frequency of an ac wave decreasesa the value of XLin a coil
A. Approaches zero
B. Gets larger positively
C. Gets larger negatively
D. Stays constant
Answer : A

46. In dividing or multiplying phasor quantitiesa ___ form is used.
A. Polar
B. Rectangular
C. Trigonometric
D. Exponential
Answer : A

47. What is the cross-sectional are of a conductor whose diameter is 0.001 inch?
A. One micron
B. One angstrom
C. One steradian
D. One circular mil
Answer : D

48. What is the value of a carbon composition resistor with the following color code: Browna whitea orangea red
A. 190 ; 10 %
B. 19 k ; 2 %
C. 19 k ; 20 %
D. 1.9 k ; 2 %
Answer : B

49. What is the resonant frequency of a circuit when L of 25 microhenrys and C of 10 picofarads are in parallel?
A. 10.1 kHz
B. 10.1 MHz
C. 101 MHz
D. 101 kHz
Answer : B

50. The power factor of a circuit is equal to
A. RZ
B. XC/Z
C. XL/Z
D. R/Z
Answer : D