Electrical Circuits 1000+ MCQ with answer for SSC Scientific Assistant

1. In an ac circuit with XL and R in seriesa the
A. Voltages across R and XL are in phase
B. Voltage across R lags the voltage across XLby 90°
C. Voltages across R and XL are 180° outof-phase
D. Voltage across R leads the voltage across XLby 90°
Answer : B

2. For maximum power transfera what is the relation between load resistance RL and internal resistance R of the voltage source?
A. RL= 2 r
B. RL= 1.5 r
C. RL= r
D. RL= 3 r
Answer : C

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

4. For series capacitorsa total charge is
A. The sum of individual charges
B. Equal to the charge of either capacitors
C. Equal to the product of the charges
D. The quotient of the charges
Answer : B

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

6. A capacitor of 0.5 F charged to 220 V is connected across an uncharged 0.5 F capacitor. What is the voltage across each capacitor?
A. 220 V
B. 150 V
C. 110 V
D. 22 V
Answer : C

7. An open resistor when checked with an ohmmeter reads
A. Zero
B. Infinite
C. High but within the tolerance
D. Low but not zero
Answer : B

8. 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

9. 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

10. Permeability is otherwise known as
A. Magnetic conductivity
B. Magnetic susceptibility
C. Electric conductivity
D. Electric susceptibility
Answer : A

11. 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

12. The second strip of an electronic resistor color-code represents
A. The multiplier
B. The second digit of the value
C. The temperature
D. The tolerance
Answer : B

13. The result of rust in electrical (wire) connection is
A. Inductance
B. Conductance
C. Impedance
D. Resistance
Answer : D

14. 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

15. The ratio of maximum value to the effective value of an alternating quantity is called
A. Form factor
B. Peak factor
C. Dynamic factor
D. Leakage factor
Answer : B

16. 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

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

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

19. Thevenin�s theorem is what form of an equivalent circuit?
A. Current
B. Voltage
C. Both current and voltage
D. Neither current nor voltage
Answer : B

20. A capacitor consists of two
A. Conductors only
B. Dielectric only
C. Conductors separated by a dielectric
D. Dielectric separated by a conductor
Answer : C

21. The average value of a triangular or sawtooth wave is _____ times its peak value.
A.
B.
C.
D.
Answer : B

22. Which of the following does not affect resistance?
A. Resistivity
B. Cross-sectional area
C. Mass
D. Length
Answer : C

23. In a circuita a passive element is one which
A. Supplies energy
B. Receives energy
C. Both supplies and receives energy
D. Attenuates signal
Answer : B

24. 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

25. In calculating maximum instantaneous power ___ voltage or current is used.
A. Peak
B. Average
C. Rms
D. Instantaneous
Answer : A

26. In a rectangular wavea the form factor is
A.
B.
C.
D.
Answer : C

27. Which of the following has a positive temperature coefficient?
A. Mica
B. Manganin
C. Silicon
D. Carbon
Answer : B

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

29. 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

30. 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

31. When two complex conjugates are subtracteda the result is a
A. Quadrature component only
B. Complex component
C. In-phase component
D. Real component
Answer : A

32. The graph between an alternating quantity and time is called
A. Sine wave
B. Curve
C. Waveform
D. A plot
Answer : C

33. What maximum voltage can be applied across the capacitor of time?
A. Working voltage
B. Surge voltage
C. Stray voltage
D. Peak voltage
Answer : B

34. 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

35. 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

36. In a multiple capacitora the plate area is
A. Increased
B. The same
C. Decreased
D. Variable
Answer : A

37. 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

38. What is expected when two 20 k a 1 watt resistor in parallel are use instead of one 10 k a 1 watt?
A. Provides higher current
B. Provides less power
C. Provides more power
D. Provides wider tolerance
Answer : C

39. What dielectric is generally employed by a variable capacitor?
A. Mica
B. Air
C. Electrolyte
D. Ceramic
Answer : B

40. The maximum power transfer theorem is used in
A. Power system
B. Electronic system
C. Refrigeration
D. Air conditioning
Answer : B

41. Norton�s theorem is ____ Thevenin�s theorem.
A. The same as
B. The converse of
C. Older that
D. More accurate than
Answer : B

42. 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

43. 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

44. Which of the following is a common material used in wire-wound resistors?
A. Manganin
B. Carbon
C. Bronze
D. German silver wire
Answer : A

45. Which of the following is a way of decreasing mutual inductance?
A. Moving the coils closer
B. Moving the coils apart
C. Decreasing the number of turns of either coil
D. Increasing the number of turns of either coil
Answer : B

46. Which of the following combination of length and cross-sectional area will give a certain volume of copper the least resistance?
A. 2L and1/2 A
B. Does not matter because the volume of copper remains the same
C. L and A
D. ½ L and 2 A
Answer : D

47. The impedance in the study of electronics is represented by resistan
A. Inductance
B. Capacitance
C. Inductance and capacitance
D. Reactance
Answer : D

48. In a series RLCcircuit
A. Increasing the frequency decreases the resistance
B. Increasing the frequency increases the resistance
C. Both XLand XCchange as frequency changes
D. Impedance will always decrease
Answer : C

49. An open inductor has
A. Zero resistance and infinite inductance
B. Infinite resistance and zero inductance
C. Infinite resistance and infinite inductance
D. Zero resistance and zero inductance
Answer : B

50. If a certain circuit has a current that is lagging the voltage by 45�a then it displays
A. Pure inductive reactance
B. Resistance and capacitance reactance
C. Resistance and inductive reactance
D. Pure capacitive reactance
Answer : C