Electrical Circuits 1000+ MCQ with answer for UPSC CDS

1. What is the most convenient way of achieving large capacitance?
A. By using multiplate construction
B. By using air as dielectric
C. By decreasing distance between plates
D. By using dielectric of low permittivity
Answer : A

2. An intermittent and non-symmetrical alternating current like that obtained from the secondary winding of an induction coil
A. Faradic current
B. Transient ac current
C. Inductive current
D. Capacitive current
Answer : A

3. Which of the following is the peakiest?
A. Square wave
B. Sinusoidal wave
C. Triangular wave
D. Rectangular wave
Answer : C

4. The rms value of a triangular or sawtooth waveform is ___ tim value.
A.
B.
C.
D.
Answer : A

5. A capacitor opposes change in
A. Voltage
B. Current
C. Voltage and current
D. Neither voltage nor current
Answer : A

6. 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

7. What is the time constant for L of 240 mH in series with R of 20 ?
A. 12 ms
B. 4.8 s
C. 83.3 s
D. 12 s
Answer : A

8. If three 100-pF capacitors are connected in seriesa then the total capacitance is
A. 300 pF
B. 100 pF
C. 50 pF
D. 33.3 pF
Answer : D

9. The admittance of a parallel RLC circuit is found to be the ___ sum of conductance and susceptances.
A. Algebraic
B. Arithmetic
C. Vector
D. Phasor
Answer : D

10. In Norton�s theorema the short circuit current is obtained by
A. Opening the load terminals
B. Shorting the load terminals
C. Opening the voltage source
D. Shorting the voltage source
Answer : B

11. What is the reciprocal of capacitance?
A. Reluctance
B. Susceptance
C. Elastance
D. Conductance
Answer : C

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

13. The potential gradient in a cable is maximum in
A. Conductor
B. Outer sheath
C. Insulation
D. Uniformly all over
Answer : A

14. When voltage is applied across a ceramic dielectric the electrostatic field p roduced is 50 times greater than air dielectric. The dielectric constant of ceramic therefore is
A.
B.
C.
D.
Answer : A

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

16. Refers to the outward-curving distortion of the lines of force near the edges of two parallel metal plates that form a capacitor.
A. Skin effect
B. Night effect
C. Edge effect
D. Hall effect
Answer : C

17. 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

18. What capacitance exists not through design but simply because two conducting surfaces are relatively close to each other?
A. Surge
B. Stray
C. Natural
D. Normal
Answer : B

19. The usual load of a dc circuit is a/an
A. Resistor
B. Capacitor
C. Inductor
D. Both inductor and capacitor
Answer : A

20. 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

21. Barium-strontium titanite dielectric material is also called
A. Ceramic
B. Polyster
C. Electrolytic
D. Bakelite
Answer : A

22. Which of the statements below is not true?
A. Current source is an active element
B. Resistor is a linear element
C. Voltage source is a passive element
D. Diode is a non-linear element
Answer : C

23. 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

24. The ohmic value of a resistor with negative temperature coefficient
A. Increases with increasing temperature
B. Increase with decreasing temperature
C. Stays unchanged with temperature change
D. Stays unaffected even with increasing temperature
Answer : B

25. According to Gauss theorema flux can be equated to
A. Charge
B. Field intensity
C. Current
D. Voltage
Answer : A

26. The open-circuit voltage at the terminal of load RL is 60V. Under the condition of maximum power transfera the load voltage will be
A. 60 V
B. 15 V
C. 20 V
D. 30 V
Answer : D

27. Which of the following is a preferred resistor value?
A.
B.
C. 43a000
D. 54a321
Answer : B

28. When capacitors are connected in seriesa the total capacitance is
A. Smaller than the smallest capacitor
B. Smaller than the largest capacitor
C. Greater than any of the capacitor
D. Greater than the largest capacitor
Answer : A

29. Property of an electric circuit that dissipates electric energy
A. Reactance
B. Impedance
C. Resistance
D. Conductance
Answer : C

30. The ___ of an alternating quantity is defined as the fractional part of a period or cycle through which the quantity has advanced from selected origin.
A. Phase
B. Frequency
C. Amplitude
D. Waveform
Answer : A

31. 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

32. In an ac circuit with a resistive branch and an inductive branch in parallela the
A. Voltage across the inductance leads the voltage across the resistance by 90°
B. Resistive branch current is 90° out of phase with the inductive branch current
C. Resistive and inductive branch currents have the same phase
D. Resistive and inductive branch currents are 180° outof-phase
Answer : B

33. Which of the following is a disadvantage of a wire-wound resistor?
A. It has reactance in radio-frequency circuits
B. It cannot handle much power
C. It draws a large amount of current
D. It cannot handle high voltage
Answer : A

34. When two in-phase sine waves that have identical frequency and amplitude are added togethera then the result is a sine wave with ___ the amplitude of either.
A. Half
B. Twice
C. Four times
D. One-fourth
Answer : B

35. 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

36. In a complex resistance-reactance planea XLis represented
A. By an axis opposite the R axis
B. By an axis perpendicular to the XC axis
C. By an axis opposite the XCaxis
D. By an axis parallel to the R axis
Answer : C

37. If resonant frequency is 10 kHz and quality factor is 50a then
A. Bandwidth is 200 Hz
B. XL= is 50a000
C. R is 50
D. XC= is 50a000
Answer : A

38. 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

39. The current is ____ times the maximum current at half-power points of a resonance curve.
A.
B.
C.
D.
Answer : A

40. In a complex number 5 + j 10a 10 is called ___ part.
A. Imaginary
B. Real
C. Conjugate
D. Integer
Answer : A

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

42. What determines the magnitude of electric current?
A. The rate at which electrons are produced
B. The type of material used
C. The current carrying capacity of the circuit
D. The rate at which electrons pass a given point
Answer : D

43. An impedance given by 90 -45� is a/an ___ impedance.
A. Inductive
B. Conductive
C. Resistive
D. Capacitive
Answer : D

44. Which of the following elements is active?
A. Resistor
B. Inductor
C. Capacitor
D. Ideal voltage source
Answer : D

45. The ratio between the reactive power and the apparent power of an ac load is called
A. Quality factor
B. Power factor
C. Power ratio
D. Reactive power
Answer : D

46. The ratio of the flux density to the electric field intensity in the dielectric is called
A. Permittivity
B. Field intensity
C. Permeability
D. Elasticity
Answer : A

47. What is the purpose of a load in an electric circuit?
A. To increase the circuit current
B. To decrease the circuit current
C. To utilize electrical energy
D. To make the circuit complete
Answer : C

48. What is the rms value of a square wave?
A. Equals its peak value
B. Equals its peak-to-peak value
C. Peak divided by square root of two
D. Peak divided by pi
Answer : A

49. 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

50. 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