AC CIRCUITS ( SINGLE PHASE)

Question 1

1. An ac device used to measure the angle between the voltage and its current.
   A. phase angle meter
   B. power factor meter
   C. demand meter
   D. reactive meter

Answer 1

B. power factor meter

Question 2

2. The total voltage in a series RL, circuit ___ the current by the angle ____?

A. Lags, of 90°
B. Lags, between 0 and 90°
C. Leads, between 0 and 90°
D. Leads, between 90° and 180°

Answer 2

C. Leads, between 0 and 90°

Question 3

3. The phase angle of a series RL circuit is the angle between the ___ phasor and the ___ phasor.

A. Resistance, inductance reactance
B. Resistance, impedance
C. Inductive reactance, impedance
D. None of these

Answer 3

B. Resistance, impedance

Question 4

4. A (n) ____ stores and returns energy to a circuit while a (n) _____ dissipate energy.

A. Capacitor, reactance
B. Capacitance, reactance
C. Inductor, resistor
D. Inductor, reactance

Answer 4

C. Inductor, resistor

Question 5

5. For an RL circuit, the power factor cannot be less than blank or greater than blank.

A. 0, 1
B. 1, 0
C. 1, -1
D. -1 0

Answer 5

A. 0, 1

Question 6

6. In an RLC circuit, the impedance at resonance is?

A. Maximum
B. Minimum
C. Infinity
D. Zero

Answer 6

B. Minimum

Question 7

7. In RLC circuit, the current at resonance is?
   A. Maximum In series circuit and minimum in parallel circuit
   B. maximum in parallel circuit and minimum in series circuit
   C. Maximum in both the circuits
   D. Minimum in both the circuits

Answer 7

A. Maximum In series circuit and minimum in parallel circuit

Question 8

8. The value of current at resonance in a series RLC circuit is affected by the value of?
   A. R
   B. C
   C. L
   D. All or these

Answer 8

A. R

Question 9

9. The current flowing in L and C at parallel resonance are?
   A. Zero
   B. Equal
   C. Infinite
   D. Different

Answer 9

B. Equal

Question 10

10. The transient currents are due to?
    A. Voltage applied to circuit
    B. Resistance of the circuit
    C. Impedance of the current
    D. Changes in stored energy in inductance an capacitance.

Answer 10

D. Changes in stored energy in inductance an capacitance.

Question 11

11. The reactance of a rotating machine that determines the current that circuit breakers will have to open to clear a fault or short-circuit is:
    A. Subtransient
    B. Synchronous
    C. Transient
    D. None of these

Answer 11

C. Transient

Question 12

12. At steady state in an RC circuit, the capacitance will act as
    A. Open circuit
    B. Short circuit
    C. Transient circuit
    D. coupled circuit

Answer 12

A. Open circuit

Question 13

13. In a purely inductive circuit, the current lags the voltage by:
    A. Zero
    B. One-fourth of a cycle
    C. One-half of a cycle
    D. Three-fourths of a cycle

Answer 13

B. One-fourth of a cycle

Question 14

41. The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to:
    A. A large inductance
    B. A large capacitance
    C. A small capacitance
    D. A large resistance

Answer 14

D. A large resistance

Question 15

15. Which of the following has the greatest effect in decreasing the oscillation frequency of an LC circuit? Using instead:
    A. L/2 and C/2
    B. L/2 and 2C
    C. 2L and C/2
    D. 2L ans 2C

Answer 15

D. 2L ans 2C

Question 16

16. The change of frequency due to the relative motion
    between the source of sound and the observer is called
    A. Beat C. Bandwidth
    B. Doppler effect D. none of these

Answer 16

B. Doppler effect

Question 17

17. In a series RL circuit , the inductor current ___ the resistor
    current
    A. lags C. is equal to
    B. leads D. is negative to

Answer 17

C. is equal to

Question 18

18. Capacitors C1 and C2 are connected in series. The
    equivalent capacitance is given by:
    A. C1C2/(C1 + C2) C. 1/(C1 + C2)
    B. (C1 + C2)/C1C2 D. C1/C2

Answer 18

A. C1C2/(C1 + C2)

Question 19

19. The inner strand of ACSR is made of
    A. Brass C. Copper
    B. Steel D. Lead

Answer 19

B. Steel