This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 37 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 37 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. How do you determine the total impedance in a parallel circuit? A) Z total = Z1 + Z2 + + Zn. B) Z total = Z1 * Z2 / (Z1 + Z2). C) Z total = max(Z1, Z2, , Zn). D) Z total = 1 / (1/Z1 + 1/Z2 + + 1/Zn). Show Answer Correct Answer: D) Z total = 1 / (1/Z1 + 1/Z2 + + 1/Zn). 2. What happens to the impedance of a series RLC circuit when the frequency is increased beyond the resonant frequency? A) It becomes zero. B) It remains constant. C) It increases. D) It decreases. Show Answer Correct Answer: C) It increases. 3. The value of an alternating quantity at a particular instant of time in a cycle is A) Instantaneous value. B) Frequency. C) All the above. D) None of the above. Show Answer Correct Answer: A) Instantaneous value. 4. What is the relationship between inductive reactance and capacitive reactance at resonance? A) Inductive reactance is always greater than capacitive reactance. B) Capacitive reactance equals zero at resonance. C) Inductive reactance and capacitive reactance are unrelated at resonance. D) Inductive reactance equals capacitive reactance at resonance. Show Answer Correct Answer: D) Inductive reactance equals capacitive reactance at resonance. 5. $2\angle25\times4\angle-10$ A) $6\angle15$. B) $8\angle250$. C) $8\angle35$. D) $8\angle15$. Show Answer Correct Answer: D) $8\angle15$. 6. If the frequency of ac is made 4 times of its initial value, the inductive reactance will A) Be 4 times. B) Be 2 times. C) Be half. D) Remain the same. Show Answer Correct Answer: A) Be 4 times. 7. Explain the concept of apparent power in AC circuits. A) Apparent power is the power consumed by resistors in a circuit. B) Apparent power is measured in watts (W) and represents only reactive power. C) Apparent power is only the real power in an AC circuit. D) Apparent power is the total power in an AC circuit, measured in volt-amperes (VA), combining real and reactive power. Show Answer Correct Answer: D) Apparent power is the total power in an AC circuit, measured in volt-amperes (VA), combining real and reactive power. 8. In a three-phase AC generator, how many degrees apart are the phases? A) 60 degrees. B) 180 degrees. C) 90 degrees. D) 120 degrees. Show Answer Correct Answer: D) 120 degrees. 9. Modified from CIE J81/II/19. An alternating current of r.m.s. magnitude 3.0 A and a steady direct current I flowing through identical resistors dissipate heat at equal rates.What is the value of current I? A) 1.5 A. B) 2.1 A. C) 3.0 A. D) 4.2 A. Show Answer Correct Answer: C) 3.0 A. 10. State whether the following statement is TRUE or FALSE; Electromagnetic waves can travel through a vacuum. A) TRUE. B) FALSE. C) All the above. D) None of the above. Show Answer Correct Answer: A) TRUE. 11. The main reason that alternating current replaced direct current for general use is: A) Ac generators do not need slip rings. B) Ac voltages may be conveniently transformed. C) Electric clocks do not work on dc. D) A given ac current does not heat a power line as much as the same dc current. Show Answer Correct Answer: B) Ac voltages may be conveniently transformed. 12. What is the main reason AC is used in the national grid? A) AC is cheaper to produce. B) AC can be easily transformed to different voltage levels for efficient transmission. C) AC is more reliable than DC. D) AC is less affected by power surges. Show Answer Correct Answer: B) AC can be easily transformed to different voltage levels for efficient transmission. 13. Why is AC preferred over DC for long-distance power transmission? A) AC is more environmentally friendly. B) AC can be transmitted at higher voltages, reducing energy losses. C) AC is easier to generate. D) AC is safer for wildlife. Show Answer Correct Answer: B) AC can be transmitted at higher voltages, reducing energy losses. 14. Phasors normally A) Do not represent real values. B) Rotate anti-clockwise. C) Do not have a direction. D) Rotate clockwise. Show Answer Correct Answer: B) Rotate anti-clockwise. 15. In which of the following circuits, the power average can be zero? A) Purely inductive circuit. B) LCR circuit. C) Both LC and LCR circuit. D) None of the above. Show Answer Correct Answer: A) Purely inductive circuit. 16. The frequency of A.C. mains in India is A) 30 c/s. B) 50 c/s. C) 60 c/s. D) 120 c/s. Show Answer Correct Answer: B) 50 c/s. 17. What is the effect of skin effect in A.C. circuits? A) No effect. B) Increased capacitance. C) Increased resistance. D) Decreased resistance. Show Answer Correct Answer: C) Increased resistance. 18. Which of the following general equations represent AC current A) $I=I_o\sin\left(2\pi ft\right)$. B) $I=I_o\sin\left(\frac{2\pi}{f}t\right)$. C) $I=I_o\cos\left(\omega t\right)$. D) $I=I_o\cos\left(t\right)$. Show Answer Correct Answer: A) $I=I_o\sin\left(2\pi ft\right)$. 19. The waveform of alternating current produced by a rotating generator is called a A) Sine wave. B) Big wave. C) Don't care because I hate this class. D) None of the above. Show Answer Correct Answer: A) Sine wave. 20. What type of connection is used in a three-phase AC circuit? A) Series connection. B) Parallel connection. C) Star and delta connections. D) Single connection. Show Answer Correct Answer: C) Star and delta connections. 21. Which best defines the meaning of the r.m.s. value of a sinusoidal alternating current? A) Steady current that delivers more power to a resistive load than the mean power of the a.c. B) Steady current that delivers the same power to a resistive load as mean power of the a.c. C) Alternating current that delivers more power to a resistive load as the mean power of the d.c. D) Alternating current that delivers the same mean power to a resistive load as the d.c. Show Answer Correct Answer: B) Steady current that delivers the same power to a resistive load as mean power of the a.c. 22. Eddy currents in the core of transformer can't be developed by A) Increasing the number of turns in secondary coil. B) Taking laminated transformer. C) Making step down transformer. D) Using a weak ac at high potential. Show Answer Correct Answer: B) Taking laminated transformer. 23. Quantity that remains unchanged in a transformer is A) Voltage. B) Current. C) Frequency. D) None of these. Show Answer Correct Answer: C) Frequency. 24. State whether the following statements is TRUE or FALSE;The electric field in an electromagnetic wave is non-oscillating. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 25. The power dissipated in the primary coil is A) 12 W. B) 0.24 W. C) 24 W. D) 6 W. Show Answer Correct Answer: B) 0.24 W. ← PreviousNext →Related QuizzesClass 12 Physics (Part I) Chapter 7 Alternating Current Quiz 1Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 2Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 3Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 4Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 5Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 6Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 7Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 8Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 9Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 10 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books