This quiz works best with JavaScript enabled. Home > Cbse > Class 12 > Science > Physics Part I > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 11 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 11 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. A 50 Hz AC is flowing in a 14 mH coil. The reactance of the circuit is A) 8.8 $\Omega$. B) 4.4 $\Omega$. C) 7.5 $\Omega$. D) 15 $\Omega$. Show Answer Correct Answer: B) 4.4 $\Omega$. 2. What is the role of inductance in AC circuits? A) Inductance only affects DC circuits. B) Inductance opposes changes in current and causes a phase shift in AC circuits. C) Inductance has no effect on phase shift in AC circuits. D) Inductance increases current flow in AC circuits. Show Answer Correct Answer: B) Inductance opposes changes in current and causes a phase shift in AC circuits. 3. In ac circuit containing R only Voltage and current are not in phase. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: B) False. 4. What is the voltage level after the step-down transformer connected to the generator? A) 132kV. B) 275kV. C) 33kV. D) 11kV. Show Answer Correct Answer: D) 11kV. 5. The type of current where charges flow in one direction A) Direct Current. B) Alternating Current. C) All the above. D) None of the above. Show Answer Correct Answer: A) Direct Current. 6. What is the main benefit of using alternating current? A) It is easy to use a transformer to change the resistance. B) It is easy to use a transformer to change the current. C) It is easy to use a transformer to change the frequency. D) It is easy to use a transformer to change the potential difference. Show Answer Correct Answer: D) It is easy to use a transformer to change the potential difference. 7. What does a Band Stop filter do? A) Blocks low frequency signals. B) Blocks high frequency signals. C) Allows a specific range of signals. D) Blocks a specific range of signals. Show Answer Correct Answer: D) Blocks a specific range of signals. 8. Typical application for zener diodes is as A) Full-wave rectifiers. B) Half-wave rectifiers. C) Voltage regulators. D) None of the above. Show Answer Correct Answer: C) Voltage regulators. 9. An inductor is connected to a source of ac voltage. The alternating voltage ..... alternating current by a phase angle of ..... radians A) Leads, $\phi$. B) Leads, $\frac{\pi}{2}$. C) In same phase with, 0. D) Lags, $\frac{\pi}{2}$. Show Answer Correct Answer: B) Leads, $\frac{\pi}{2}$. 10. What is a current that fluctuates back and forth within a circuit called? A) Direct Current. B) Static Current. C) Alternating Current. D) Oscillating Current. Show Answer Correct Answer: D) Oscillating Current. 11. The resistance of a coil for d.c. is in ohms .In a.c., the resistance A) Will decrease. B) Will increase. C) Will be zero. D) Will remain same. Show Answer Correct Answer: B) Will increase. 12. How many alternations are completed when the conductor passes one pair of magnetic poles? A) Two alternations. B) One alternation. C) Three alternations. D) Four alternations. Show Answer Correct Answer: A) Two alternations. 13. The primary of a 3:1 step-up transformer is connected to a source and the secondary is connected to a resistor R. The power dissipated by R in this situation is P. If R is connected directly to the source it will dissipate a power of: A) P/3. B) 9P. C) P/9. D) 3P. Show Answer Correct Answer: C) P/9. 14. The alternating current is the flow of electric current whose A) Always change its magnitude. B) Have random change of magnitude and direction. C) Periodically change its magnitude and direction. D) Always change its direction. Show Answer Correct Answer: C) Periodically change its magnitude and direction. 15. Fill in the blank:Hair growth will be softer to the ..... A) Touch. B) Taste. C) Eye. D) Smell. Show Answer Correct Answer: A) Touch. 16. What is the significance of the phasor representation in AC analysis? A) It complicates the calculations of AC circuits. B) Phasor representation is only useful for DC analysis. C) Phasor representation simplifies AC analysis by converting sinusoidal signals into complex numbers, facilitating easier calculations and visualization of phase relationships. D) Phasors are used to represent non-sinusoidal signals. Show Answer Correct Answer: C) Phasor representation simplifies AC analysis by converting sinusoidal signals into complex numbers, facilitating easier calculations and visualization of phase relationships. 17. In a R, L, C circuit, three elements are connected in series by a.c. source. If frequency is less than resonating frequency, then net impedance of the circuit will be A) Capacitive. B) Inductive. C) Pure resistive. D) None of these. Show Answer Correct Answer: A) Capacitive. 18. What is the waveform called that results from the graphing of values produced by the motion of the conductor? A) Pulse wave. B) Square wave. C) Triangle wave. D) Sine wave. Show Answer Correct Answer: D) Sine wave. 19. ..... is the rate at which current changes direction per second A) Frequency. B) Cycle. C) All the above. D) None of the above. Show Answer Correct Answer: A) Frequency. 20. What is another name for alternating current? A) Radio frequency RF. B) Static electricity. C) Direct current DC. D) Electromagnetic induction. Show Answer Correct Answer: A) Radio frequency RF. 21. Consider the following statements and then select the true/false statements.1. Most of the electrical device we require ac voltage2. Most of the electrical energy sold by power companies is transmitted and distributed as alternating current3. AC voltage can be easily and efficiently converted from one to the other by means of transformers. A) T, T, F. B) T, T, T. C) T, F, F. D) T, F, T. Show Answer Correct Answer: B) T, T, T. 22. When a.c. is applied to a purely capacitive circuit, what is the phase relation between current and emf? A) Current leads emf by $\pi/2$. B) Current lags emf by $\pi/2$. C) Current and emf are in phase. D) Current leads emf by $\pi/4$. Show Answer Correct Answer: A) Current leads emf by $\pi/2$. 23. An alternating voltage has the equation v = 141.4 sin 377t . Determine the frequency. A) 60 Hz. B) 50 Hz. C) 40 Hz. D) 70 Hz. Show Answer Correct Answer: A) 60 Hz. 24. The electric current in a circuit is given by $i=i_o\left(\frac{t}{\tau}\right)$ $t=0$ $t=\tau$ A) $\frac{2i_o}{\sqrt{3}}$. B) $\frac{\sqrt{2}i_o}{3}$. C) $\frac{i_o}{\sqrt{3}}$. D) $\frac{i_o}{\sqrt{2}}$. Show Answer Correct Answer: C) $\frac{i_o}{\sqrt{3}}$. 25. One complete wave form including positive half cycle and negative half cycle is called A) Cycle. B) Frequency. C) All the above. D) None of the above. Show Answer Correct Answer: A) Cycle. 26. How is the power in a three-phase system calculated? A) $P = VI$. B) $P = \sqrt{3} \times VI \times\cos(\phi)$. C) $P = V^2/R$. D) $P = I^2R$. Show Answer Correct Answer: B) $P = \sqrt{3} \times VI \times\cos(\phi)$. 27. When frequency decreases, capacitive reactance ..... A) Remains the same. B) May increase or decrease. C) Decreases. D) Increases. Show Answer Correct Answer: D) Increases. 28. What in causes a lightbulb to flicker? A) Alternating Currents. B) Direct Currents. C) All the above. D) None of the above. Show Answer Correct Answer: A) Alternating Currents. 29. A capacitor of 50 pF is connected to an a.c source of frequency 1kHz. Calculate its reactance A) 1.1x10$^{6}$ Hz. B) 3.1x10$^{6}$ Hz. C) 0.1x10$^{6}$ Hz. D) 2.1x10$^{6}$ Hz. Show Answer Correct Answer: B) 3.1x10$^{6}$ Hz. 30. The total voltage transmitted from the plant is A) 3 kV. B) 4 kV. C) 0.5 kV. D) 7 kV. Show Answer Correct Answer: D) 7 kV. 31. What does the root mean square (r.m.s.) voltage represent? A) The voltage at the midpoint of the cycle. B) The average of all instantaneous voltages. C) The effective value of the alternating voltage. D) The peak voltage divided by two. Show Answer Correct Answer: C) The effective value of the alternating voltage. 32. The total opposition to current flow in an AC circuit is known as ..... A) Inductive reactance. B) Impedance. C) Resistance. D) Capacitive reactance. Show Answer Correct Answer: B) Impedance. 33. Which type of current is used in a microwave A) Alternating Current (AC). B) Direct Current (DC). C) All the above. D) None of the above. Show Answer Correct Answer: A) Alternating Current (AC). 34. What is the main characteristic of direct current? A) It flows in one direction. B) It comes from power plants. C) It is used in homes. D) It reverses direction. Show Answer Correct Answer: A) It flows in one direction. 35. Which of the following is true of the current in a capacitive circuit? A) It is the same as the voltage. B) It lags the voltage. C) It counteracts the voltage. D) It leads the voltage. Show Answer Correct Answer: D) It leads the voltage. 36. What is a key reason for using high voltage in AC transmission lines? A) To increase the speed of electricity flow. B) To reduce energy losses by decreasing current. C) To make the lines more durable. D) To allow for easier maintenance. Show Answer Correct Answer: B) To reduce energy losses by decreasing current. 37. What type of transformer increases the voltage from primary to secondary coil? A) Step-up Transformer. B) Step-down Transformer. C) Auto Transformer. D) Isolation Transformer. Show Answer Correct Answer: A) Step-up Transformer. 38. When the current increases in an AC circuit, what role does inductance play? A) It reduces the current. B) It increases the current. C) It causes the overcurrent protection to open. D) It plays no role at all. Show Answer Correct Answer: A) It reduces the current. 39. A device that uses an electromagnet to measure electric current is a(n) ..... A) Commutator. B) Galvanometer. C) Electric motor. D) Generator. Show Answer Correct Answer: B) Galvanometer. 40. In a pure resistor circuit, ..... A) The voltage and current are in antiphase. B) The voltage leads current by $\frac{\pi}{2}$. C) The voltage and current are in phase. D) The current leads voltage by $\frac{\pi}{2}$. Show Answer Correct Answer: C) The voltage and current are in phase. 41. What does RLC stand for A) Remote Logic Control. B) Resistor Logic Capacitor Circuit. C) Resistor Inductor Capacitor Circuit. D) None of the above. Show Answer Correct Answer: C) Resistor Inductor Capacitor Circuit. 42. The phase angle between current and voltage is A) 55$^\circ$4'. B) 53$^\circ$4'. C) 50$^\circ$. D) 63$^\circ$9'. Show Answer Correct Answer: A) 55$^\circ$4'. 43. The current flowing in purely capacitive circuit connected with ac source A) Conventional current. B) Electronic current. C) Wattless current. D) None. Show Answer Correct Answer: C) Wattless current. 44. The two windings of a conventional transformer are known as the ..... A) High voltage winding and low voltage winding. B) Primary winding and secondary winding. C) Mutual winding and inductive winding. D) Step-up winding and step-down winding. Show Answer Correct Answer: B) Primary winding and secondary winding. 45. How do transformers step up or step down voltage in AC systems? A) Transformers step up or step down voltage by using the turns ratio of their coils. B) Transformers rely on magnetic fields to increase or decrease voltage. C) Transformers convert AC to DC to change voltage. D) Transformers use capacitors to adjust voltage levels. Show Answer Correct Answer: A) Transformers step up or step down voltage by using the turns ratio of their coils. 46. The relationship between the inductive reactance of an inductor is A) Directly proportional to the frequency of the AC source. B) Inversely proportional to the frequency of the AC source. C) Inversely proportional to the inductance of a inductor. D) None of the above. Show Answer Correct Answer: A) Directly proportional to the frequency of the AC source. 47. What type of current is represented by the following I-t graph A) DC current. B) Pulsating Current. C) AC current. D) Time varying current. Show Answer Correct Answer: C) AC current. 48. What is meant by Alternating Current? A) An electric current whose direction change periodically. B) An electric current whose magnitude change periodically. C) An electric current whose magnitude and direction change periodically. D) An electric current whose magnitude or direction change periodically. Show Answer Correct Answer: C) An electric current whose magnitude and direction change periodically. 49. What happens to the Self-inductance when the current in the coil becomes double its original value? A) Becomes infinity. B) Becomes half. C) No Change. D) Becomes four times. Show Answer Correct Answer: C) No Change. 50. The opposition offered by a coil to the flow of alternating current is called (disregard resistance) A) Impedance. B) Reluctance. C) Inductive reactance. D) None of the above. Show Answer Correct Answer: C) Inductive reactance. 51. Calculate the r.m.s value of a.c if its peak value is 10A A) 7.07A. B) 9.07A. C) 5.07A. D) 2.07A. Show Answer Correct Answer: A) 7.07A. 52. The selectivity of a series LCR AC circuit is large, when A) L is large and R is large. B) L is small and R is small. C) L is large and R is small. D) L = R. Show Answer Correct Answer: C) L is large and R is small. 53. When electrons in the transmitting antenna vibrate 94000 times per second, they produce radio waves having frequency A) 9.4 kHz. B) 940 kHz. C) 94kHz. D) None of these. Show Answer Correct Answer: C) 94kHz. 54. Reactance increases with an increase in ..... A) Capacitance. B) Magnetism. C) Inductance. D) Resistance. Show Answer Correct Answer: C) Inductance. 55. Multimeter used to measure A) AC voltage. B) DC voltage. C) Resistance. D) All of the above. Show Answer Correct Answer: D) All of the above. 56. Through which material will magnetic lines of force pass the most readily? A) Copper. B) Iron. C) Aluminum. D) None of the above. Show Answer Correct Answer: B) Iron. 57. DC stands for ..... and is used in batteries. A) Distant Current. B) Don't Current. C) Direct Current. D) None of the above. Show Answer Correct Answer: C) Direct Current. 58. A half-wave rectification circuit needs only ..... diode. A) 4. B) 1. C) 3. D) 2. Show Answer Correct Answer: B) 1. 59. How does resistance affect a circuit? A) The relationship of the resistance and a circuit is indirect. B) The relationship of the resistance and a circuit is direct. C) All the above. D) None of the above. Show Answer Correct Answer: A) The relationship of the resistance and a circuit is indirect. 60. This occurs when 2 objects are rubbed together. A) Induction. B) Attract. C) Repel. D) Friction. Show Answer Correct Answer: D) Friction. ← PreviousNext →Related QuizzesScience QuizzesClass 12 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 8 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books