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 14 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 14 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. An alternating current is one that ..... A) Changes direction periodically. B) Flows in a fixed direction. C) Changes only magnitude periodically. D) Has a fixed magnitude. Show Answer Correct Answer: A) Changes direction periodically. 2. A vector quantity has A) Only magnitude. B) Only direction. C) Both (a) and (b). D) None of these. Show Answer Correct Answer: C) Both (a) and (b). 3. Which graph represents current and voltage in capacitive circuit? A) In phase. B) Current ahead of voltage. C) Voltage ahead of current. D) Both zero. Show Answer Correct Answer: B) Current ahead of voltage. 4. What is the term for the opposition to current flow in an inductor? A) Inductive reactance. B) Impedance. C) Capacitive reactance. D) Resistance. Show Answer Correct Answer: A) Inductive reactance. 5. Which of the following conditions exists in a circuit of pure resistance? A) The voltage and current are 180$^\circ$ out of phase. B) The voltage and current are 270$^\circ$ out of phase. C) The voltage and current are 90$^\circ$ out of phase. D) The voltage and current are in phase. Show Answer Correct Answer: D) The voltage and current are in phase. 6. A family wants to use solar panels to power their home. What device is needed to convert the DC output of solar panels to AC for household use? A) Fuse. B) Inverter. C) Capacitor. D) Transformer. Show Answer Correct Answer: B) Inverter. 7. A transformer has an efficiency of 80%. It works at 4kW and 100V. If secondary voltage is 240V, the current in primary coil is A) 10A. B) 4A. C) 0.4A. D) 40A. Show Answer Correct Answer: D) 40A. 8. In a purely resistive AC circuit where 240V is applied across a 10$\Omega$ resistor, the amperage is ..... A) 10A. B) 120A. C) 60A. D) 24A. Show Answer Correct Answer: D) 24A. 9. The quantity that limits AC more at high frequency: A) Capacitance. B) Resistance. C) Inductance. D) Emf. Show Answer Correct Answer: C) Inductance. 10. In an RLC circuit, power loss can take place in A) R. B) L. C) C. D) L and C. Show Answer Correct Answer: A) R. 11. Induced emf in a conductor of length l moving perpendicular to uniform magnetic field B with velocity v is A) E = Blv. B) E = Bv$^{2}$l. C) E = Bl/v. D) E = Bv/l. Show Answer Correct Answer: A) E = Blv. 12. How does impedance affect the flow of current in an AC circuit? A) Impedance affects the flow of current in an AC circuit by resisting it. Higher impedance leads to a decrease in current flow. B) Impedance in an AC circuit causes a direct current flow. C) Impedance has no effect on current flow in an AC circuit. D) Higher impedance leads to an increase in current flow. Show Answer Correct Answer: A) Impedance affects the flow of current in an AC circuit by resisting it. Higher impedance leads to a decrease in current flow. 13. The opposition to the flow of alternating current offered by a capacitor is called A) Capacitance. B) Inductive Reactance. C) Capacitive Reactance. D) None of the above. Show Answer Correct Answer: C) Capacitive Reactance. 14. A lamp is connected to a sinusoidal supply. The maximum power transferred by the lamp is 50 W. What is the average power of the lamp. A) 25 W. B) 100 W. C) 10 W. D) 50 W. Show Answer Correct Answer: A) 25 W. 15. What is the frequency of ac mains in India? A) 120 Hz. B) 50 Hz. C) 30 Hz. D) 60 Hz. Show Answer Correct Answer: B) 50 Hz. 16. Which of the following consumes net power in one cycle? A) Inductor. B) Capacitor. C) Resistance. D) All Devices consume Zero Average Power. Show Answer Correct Answer: C) Resistance. 17. Which of the following is NOT a source of direct current? A) Fuel cells. B) Solar cells. C) Power plants. D) Batteries. Show Answer Correct Answer: C) Power plants. 18. Which of the following choices best gives the benefit(s) of using AC over using DC? A) The length of wires is less relevant. B) Power may be transferred over long distances using higher voltage and low current. C) The potential difference may be varied using transformers. D) All of the above answers are benefits of AC over DC. Show Answer Correct Answer: D) All of the above answers are benefits of AC over DC. 19. In an LCR circuit A) Impedance is equal to reactance. B) The ratio between effective voltage to effective current is called reactance. C) At resonance the resistance is equal to the reactance. D) At resonance the net reactance is zero. Show Answer Correct Answer: D) At resonance the net reactance is zero. 20. What is the condition for resonance in an L-C circuit? A) R = 0. B) XL = XC. C) Im = 0. D) V = 0. Show Answer Correct Answer: B) XL = XC. 21. What is the other name for direct current? A) AC. B) DC. C) Hertz. D) Oscilloscope. Show Answer Correct Answer: B) DC. 22. The distance from the center line to the top of a crest or to the bottom of a trough is ..... A) Amplitude. B) Cycle. C) Frequency. D) None of the above. Show Answer Correct Answer: A) Amplitude. 23. Fill in the blank:Hair growth will be ..... A) Faster. B) Stronger. C) Thicker. D) Weaker. Show Answer Correct Answer: D) Weaker. 24. What does an oscilloscope trace show for an alternating current? A) The maximum potential difference. B) The frequency. C) The resistance. D) The current direction. Show Answer Correct Answer: B) The frequency. 25. How is the frequency of an alternating current measured? A) Amperes. B) Ohms. C) Volts. D) Hertz (Hz). Show Answer Correct Answer: D) Hertz (Hz). 26. The time constant of an R-L circuit is found using what formula? A) TC=L/R. B) ABC=123. C) TC=R/L. D) None of the above. Show Answer Correct Answer: A) TC=L/R. 27. What is the voltage level after the final step-down transformer before reaching residential areas? A) 400V. B) 11kV. C) 33kV. D) 230V. Show Answer Correct Answer: D) 230V. 28. What is HZ when relating to frequency? A) Hz is cycles per second. B) Hz is height gained per second. C) Hz is height gained per minute. D) Hz is cycles per minute. Show Answer Correct Answer: A) Hz is cycles per second. 29. What does the period of a wave represent? A) The distance between two peaks of the wave. B) The number of cycles per second. C) The amount of time for one wavelength to complete. D) The maximum amplitude of the wave. Show Answer Correct Answer: C) The amount of time for one wavelength to complete. 30. The frequency of AC mains in our country is A) 50 cycles/s. B) 60 cycles/s. C) 0 cycles/s. D) 30 cycles/s. Show Answer Correct Answer: A) 50 cycles/s. 31. In an oscillating LC circuit the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is A) $\frac{Q}{\sqrt{3}}$. B) Q. C) Q/2. D) $\frac{Q}{\sqrt{2}}$. Show Answer Correct Answer: D) $\frac{Q}{\sqrt{2}}$. 32. In a series LCR circuit which of the following statements is/are true/ false?1. At resonance impedance becomes minimum and current becomes maximum2. At resonance current is in phase with applied voltage3. Resonant frequency depends upon the resistance of the circuit A) T, F, T. B) F, T, F. C) T, T, F. D) T, F, F. Show Answer Correct Answer: C) T, T, F. 33. The unit of inductive reactance is: A) Ohm. B) Henry. C) Farad. D) Ampere. Show Answer Correct Answer: B) Henry. 34. Define resonance in the context of AC circuits. A) Resonance in AC circuits is the condition where the circuit's natural frequency matches the frequency of the applied AC signal, resulting in increased amplitude. B) Resonance occurs only in DC circuits. C) Resonance happens when the circuit is short-circuited. D) Resonance is the process of converting AC to DC. Show Answer Correct Answer: A) Resonance in AC circuits is the condition where the circuit's natural frequency matches the frequency of the applied AC signal, resulting in increased amplitude. 35. The unit of impedance is same as that of: A) Power. B) Current. C) Voltage. D) Resistance. Show Answer Correct Answer: D) Resistance. 36. The time constant of RC circuit is A) 1/CR. B) R/C. C) C/R. D) CR. Show Answer Correct Answer: D) CR. 37. An inductive circuit contains a resistance of 10 ohm and an inductance of 2.0 henry. If an ac voltage of 120 volt and frequency of 60 Hz is applied to this circuit, the current in the circuit would be nearly A) 0.48 amp. B) 0.16 amp. C) 0.80 amp. D) 0.32 amp. Show Answer Correct Answer: B) 0.16 amp. 38. The current that flows steadily in one direction. A) AC. B) DC. C) Induced current. D) None of these. Show Answer Correct Answer: B) DC. 39. What is different about the speed of sound waves vs. the speed of light? A) Sound waves are the FASTEST in solids (high density), while light waves are the FASTEST in gas (or no molecules). B) Sound waves are the FASTEST in gas (low density), while light waves are the FASTEST in solids. C) Both have the same speed all the time. D) Both are the FASTEST in the air or gas (low density). Show Answer Correct Answer: A) Sound waves are the FASTEST in solids (high density), while light waves are the FASTEST in gas (or no molecules). 40. Rotating Vectors are called as A) There is no such Vector. B) Tensors. C) Rotating Vectors. D) Phasors. Show Answer Correct Answer: D) Phasors. 41. If impedance of an AC circuit increases, current will: A) Become zero. B) Remain same. C) Decrease. D) Increase. Show Answer Correct Answer: C) Decrease. 42. Which of the following is a good electrical insulator? A) Iron. B) Plastic. C) Copper. D) Aluminum. Show Answer Correct Answer: B) Plastic. 43. The power is transmitted from a power house on high voltage ac because ..... A) It is difficult to generate power at low voltage. B) Electric current travels faster at higher volts. C) Chances of stealing transmission lines are minimized. D) It is more economical due to less power wastage. Show Answer Correct Answer: D) It is more economical due to less power wastage. 44. How do inductors and capacitors store energy differently in AC circuits? A) Inductors and capacitors both store energy in electric fields. B) Inductors store energy in an electric field; capacitors store energy in a magnetic field. C) Inductors store energy as heat; capacitors store energy in a magnetic field. D) Inductors store energy in a magnetic field; capacitors store energy in an electric field. Show Answer Correct Answer: D) Inductors store energy in a magnetic field; capacitors store energy in an electric field. 45. At resonance, inductive reactance is: A) Less than capacitive. B) Equal to capacitive. C) Zero. D) Greater than capacitive. Show Answer Correct Answer: B) Equal to capacitive. 46. Which type of current is used in a battery-powered flashlight? A) Direct current. B) Fuel cell current. C) Solar current. D) Alternating current. Show Answer Correct Answer: A) Direct current. 47. What is meant by rms current? A) Steadyvoltage which delivers the same average power as the a.c. to aresistive load. B) Steadycurrent which delivers the same average power as the a.c. to aresistive load. C) Alternating converted tod.c. D) The square root of the mean of the squares of all values of voltage in one full cycle. Show Answer Correct Answer: B) Steadycurrent which delivers the same average power as the a.c. to aresistive load. 48. In rectification, what is the purpose of a smoothing capacitor? A) To increase the peak voltage. B) To reduce the ripple in the output voltage. C) To convert AC to DC. D) To store energy for later use. Show Answer Correct Answer: B) To reduce the ripple in the output voltage. 49. How does the inductive reactance change with frequency in an AC circuit? A) Inductive reactance decreases with increasing frequency. B) Inductive reactance increases with increasing frequency. C) Inductive reactance remains constant regardless of frequency. D) Inductive reactance is not affected by frequency. Show Answer Correct Answer: B) Inductive reactance increases with increasing frequency. 50. What happens to the electromotive force (EMF) in alternating current (a.c.)? A) It periodically reverses its direction. B) It remains constant. C) It increases over time. D) It decreases over time. Show Answer Correct Answer: A) It periodically reverses its direction. 51. What are the common applications of AC? A) Powering homes and businesses, operating electric motors, supplying electricity to appliances and lighting systems. B) Heating water in boilers. C) Charging electric vehicles. D) Transmitting data over the internet. Show Answer Correct Answer: A) Powering homes and businesses, operating electric motors, supplying electricity to appliances and lighting systems. 52. Impedance of the circuit is A) 42.26 $\Omega$. B) 15 $\Omega$. C) 30 $\Omega$. D) 21.13 $\Omega$. Show Answer Correct Answer: D) 21.13 $\Omega$. 53. What is the phase angle between the voltages of the inductor and capacitor in a RLC series circuit? A) Zero. B) 270$^\circ$. C) 180$^\circ$. D) 90$^\circ$. Show Answer Correct Answer: C) 180$^\circ$. 54. Jika Nilai XL = XC, maka rangkaian tersebut bersifat ..... A) Induktif. B) Induktif Murni. C) Kapasitif Murni. D) Resistif. E) Kapasitif. Show Answer Correct Answer: D) Resistif. 55. What is the formula for impedance in an RL circuit? A) $Z=R+X_L$. B) $Z=\sqrt{R+X_L}$. C) $Z=\sqrt{R^2+X_L^2}$. D) None of the above. Show Answer Correct Answer: C) $Z=\sqrt{R^2+X_L^2}$. 56. If a conductor 0.2m long moves with a velocity of 0.3m/s in a magnetic field of 5T, calculate the emf induced. A) 3 V. B) 30 V. C) 0.3 V. D) 0.03 V. Show Answer Correct Answer: C) 0.3 V. 57. The period of an ac waveform is A) The same as frequency. B) Time required to complete one cycle. C) Expressed in amperes. D) None of the above. Show Answer Correct Answer: B) Time required to complete one cycle. 58. What is the primary advantage of A.C. over D.C.? A) Higher danger level. B) Lower efficiency. C) More complex circuitry. D) Easier transmission over long distances. Show Answer Correct Answer: D) Easier transmission over long distances. 59. The rms value of an ac current is: A) Its peak value. B) That steady current that will charge a battery at the same rate. C) Its average value. D) That steady current that produces the same rate of heating in a resistor. Show Answer Correct Answer: D) That steady current that produces the same rate of heating in a resistor. 60. If frequency becomes zero, AC circuit behaves like: A) Resonant circuit. B) Capacitive circuit. C) Inductive circuit. D) DC circuit. Show Answer Correct Answer: D) DC circuit. ← 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