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 3 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 3 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. What does RMS means? A) Really Monday Stinks. B) Root Minus Square. C) Root Mean Square. D) Root Minus Subtraction. Show Answer Correct Answer: C) Root Mean Square. 2. A 44 mH inductor is connected to a 220 V, 50 Hz ac supply. Determine the rms value of the current in the circuit. A) 4.40 A. B) 1.38 A. C) 50.0 A. D) 15.9 A. Show Answer Correct Answer: D) 15.9 A. 3. Which type of current goes back and forth in a circuit? 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). 4. What type of transformer is used to increase the voltage from 25kV to 275kV? A) Isolation transformer. B) Auto transformer. C) Step-down transformer. D) Step-up transformer. Show Answer Correct Answer: D) Step-up transformer. 5. If the peak current in an AC circuit is 3.0 A, what is the rms value of the current? A) 3.0 A. B) 2.12 A. C) 4.24 A. D) 1.5 A. Show Answer Correct Answer: D) 1.5 A. 6. AC is a result of A) Chemical reaction. B) Electromagnetic reaction. C) Biological reaction. D) None of the above. Show Answer Correct Answer: B) Electromagnetic reaction. 7. A sine wave has a Peak-to-Peak voltage of 88Volts, what is the RMS voltage of this sine wave? A) 62.23 Volts. B) 44 Volts. C) 88 Volts. D) 31.1 Volts. Show Answer Correct Answer: D) 31.1 Volts. 8. An alternating current is given by the equation $i=i_1\\cos\omega t+i_2\\sin\omega t$ A) $\sqrt{2}\left(i_1^2+i_2^2\right)^{\frac{1}{2}}$. B) $\frac{1}{\sqrt{2}}\left(i_1+i_2\right)$. C) $\frac{1}{\sqrt{2}}\left(i_1+i_2\right)^2$. D) $\frac{1}{\sqrt{2}}\left(i_1^2+i_2^2\right)^{\frac{1}{2}}$. Show Answer Correct Answer: D) $\frac{1}{\sqrt{2}}\left(i_1^2+i_2^2\right)^{\frac{1}{2}}$. 9. The opposition to current flow offered by the capacitance of a circuit is known as ..... A) Capacitive reactance. B) Inductive reactance. C) Pure resistance. D) Mutual inductance. Show Answer Correct Answer: A) Capacitive reactance. 10. Which type of current only flows in 1 direction around a circuit? A) Direct Current (DC). B) Alternating Current (AC). C) All the above. D) None of the above. Show Answer Correct Answer: A) Direct Current (DC). 11. Average Power transferred to the capacitor is A) 15W. B) Zero. C) 11W. D) 5W. Show Answer Correct Answer: B) Zero. 12. Which of the following conditions exists in a circuit of pure inductance? A) The voltage and current are 180$^\circ$ out of phase. B) The voltage and current are 90$^\circ$ out of phase. C) The voltage and current are 120$^\circ$ out of phase. D) The voltage and current are in phase. Show Answer Correct Answer: B) The voltage and current are 90$^\circ$ out of phase. 13. The power factor in a circuit connected to an ac A) Unity when the circuit contains an ideal resistance only. B) Unity when the circuit contains an ideal capacitance only. C) Zero when the circuit contains an ideal resistance only. D) Unity when the circuit contains an ideal inductance only. Show Answer Correct Answer: A) Unity when the circuit contains an ideal resistance only. 14. A technician needs to repair a faulty AC circuit in a home. What steps should they take to ensure safety before starting the repair? A) Leave the power on and use metal tools. B) Turn off the main power supply, use insulated tools, and wear protective gear. C) Work quickly to avoid danger. D) Use water to clean the area. Show Answer Correct Answer: B) Turn off the main power supply, use insulated tools, and wear protective gear. 15. What does the acronym ICE stand for? A) Voltage Leads Current in Capacitor Circuits. B) Voltage Lags Current in Inductor Circuits. C) Energy Last Internal. D) Current Leads Voltage in Capacitor Circuits. Show Answer Correct Answer: D) Current Leads Voltage in Capacitor Circuits. 16. A series LCR circuit is connected to a variable-frequency source with values:$V = 230$ $L = 5$ $C = 80$ $R = 40$ A) 5.00 Hz. B) 8.84 Hz. C) 50.0 Hz. D) 7.96 Hz. Show Answer Correct Answer: D) 7.96 Hz. 17. Using the phasor diagram of an LCR series circuit with $V_L > V_C$ A) Z = $\sqrt{R^2 + (X_L-X_C)^2}$. B) Z = $\sqrt{R^2 + X_L^2 + X_C^2}$. C) Z = R + X L + X C. D) Z = $\sqrt{X_L^2-X_C^2}$. Show Answer Correct Answer: A) Z = $\sqrt{R^2 + (X_L-X_C)^2}$. 18. A student wants to design a simple AC circuit for a lamp. Which components are essential for the circuit to work safely? A) Lamp, wire, battery. B) Lamp, wire, fuse, switch. C) Lamp, wire, resistor. D) Lamp, wire, solar cell. Show Answer Correct Answer: B) Lamp, wire, fuse, switch. 19. What is the phase relationship between voltage and current in a purely resistive AC circuit? A) Current leads voltage by 90 degrees. B) The phase relationship is that voltage and current are in phase. C) Voltage and current are 180 degrees out of phase. D) Voltage leads current by 90 degrees. Show Answer Correct Answer: B) The phase relationship is that voltage and current are in phase. 20. What does a High-Pass 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: A) Blocks low frequency signals. 21. What is the difference in frequency between the two currents? A) An Alternating Current has a frequency of 0hz, and a Direct Current usually has a frequency of 60hz. B) They both have a frequency of 60hz. C) An Alternating Current usually has a frequency of 60hz, and a Direct Current normally has a higher frequency. D) An Alternating Current usually has a frequency of 60hz, and a Direct Current has a frequency of 0hz. Show Answer Correct Answer: D) An Alternating Current usually has a frequency of 60hz, and a Direct Current has a frequency of 0hz. 22. In a pure inductor ac circuit A) Current lead voltage by 90'. B) Voltage lead current by 90'. C) Both current and voltage are in phase. D) Current and voltage are out of phase. Show Answer Correct Answer: B) Voltage lead current by 90'. 23. The value of current in the primary coil is A) 2 A. B) 0.02 A. C) 0.2 A. D) 0.4 A. Show Answer Correct Answer: B) 0.02 A. 24. UCLES N93/I/18. A sinusoidal alternating current of peak value I$_{o}$ passes through a heater of resistance R.What is the mean power output of the heater? A) $\frac{I_o^2R}{\sqrt{2}}$. B) $I_o^2R$. C) $\frac{I_o^2R}{2}$. D) $I_o^2R\sqrt{2}$. E) $2I_o^2R$. Show Answer Correct Answer: C) $\frac{I_o^2R}{2}$. 25. What is the relationship between frequency and capacitive reactance in an AC circuit? A) It is independent of the capacitance value. B) It remains constant regardless of frequency. C) It is directly proportional. D) It is inversely proportional. Show Answer Correct Answer: D) It is inversely proportional. 26. Which of the following coils is likely to show the lowest inductance? A) A coil with a short core. B) A coil with many turns. C) A coil with a narrow diameter. D) A coil with a magnetic core. Show Answer Correct Answer: C) A coil with a narrow diameter. 27. Alternating current can be represented by: A) Sine curve. B) Cos curve. C) Neither sine nor cos. D) Both sine and cos. Show Answer Correct Answer: D) Both sine and cos. 28. In a purely capacitive AC circuit, the current A) None of the given answers. B) Is in phase with the voltage. C) Lags the voltage by 90$^\circ$. D) Leads the voltage by 90$^\circ$. Show Answer Correct Answer: D) Leads the voltage by 90$^\circ$. 29. What does the number of cycles per second represent in alternating current? A) Resistance. B) Current. C) Frequency. D) Voltage. Show Answer Correct Answer: C) Frequency. 30. The average value of AC over one complete cycle is: A) Maximum. B) Zero. C) Rms value. D) Peak value. Show Answer Correct Answer: B) Zero. 31. Explain the concept of resonance in RLC circuits. A) Resonance occurs when the circuit is powered by a DC source. B) Resonance in RLC circuits is the condition where inductive and capacitive reactances are equal, maximizing current at the resonant frequency. C) Resonance is achieved by increasing the resistance in the circuit. D) Resonance happens when the circuit is short-circuited. Show Answer Correct Answer: B) Resonance in RLC circuits is the condition where inductive and capacitive reactances are equal, maximizing current at the resonant frequency. 32. The basis for transformer operation in the use of alternating current is mutual A) Inductance. B) Capacitance. C) Reactance. D) None of the above. Show Answer Correct Answer: A) Inductance. 33. What is the formula for capacitive reactance? A) $\omega C$. B) $\frac{1}{\omega C}$. C) $\frac{1}{\omega L}$. D) $\omega L$. Show Answer Correct Answer: B) $\frac{1}{\omega C}$. 34. An electric current which periodically reverses direction and changes its magnitude continuously with time A) Altrenating current. B) Direct current. C) All the above. D) None of the above. Show Answer Correct Answer: A) Altrenating current. 35. When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220V. This means A) Input voltage cannot be ac voltage, but a dc voltage. B) Maximum input voltage is 220V. C) The meter reads not v but < v2 > and is calibrated to read $\sqrt{}$. D) The pointer of the meter is stuck by some mechanical defect. Show Answer Correct Answer: C) The meter reads not v but < v2 > and is calibrated to read $\sqrt{}$. 36. An alternating current is set up in an LRC circuit. For which of the following circuit elements does the voltage lead the current by 90$^\circ$? A) Inductor only. B) Resistor only. C) Capacitor only. D) Resistor and capacitor only. Show Answer Correct Answer: A) Inductor only. 37. What happens when the conductor moves parallel to the lines of magnetic force? A) The magnetic field collapses. B) No emf is generated. C) Maximum emf is generated. D) The conductor heats up. Show Answer Correct Answer: B) No emf is generated. 38. What does an oscilloscope trace show for a direct current? A) The resistance. B) The current direction. C) The maximum potential difference. D) The frequency. Show Answer Correct Answer: C) The maximum potential difference. 39. What is the significance of the phase angle in AC circuits? A) The phase angle determines the resistance in the circuit. B) The phase angle signifies the phase difference between voltage and current, affecting power factor and power transfer efficiency. C) The phase angle is irrelevant in AC circuits. D) The phase angle indicates the frequency of the circuit. Show Answer Correct Answer: B) The phase angle signifies the phase difference between voltage and current, affecting power factor and power transfer efficiency. 40. The total resistance of the wire i A) 15 $\Omega$. B) 35 $\Omega$. C) 30 $\Omega$. D) 25 $\Omega$. Show Answer Correct Answer: A) 15 $\Omega$. 41. In a transformer with two windings, which one is the primary? The winding A) With the least turns. B) Connected to the source. C) Connected to the load. D) None of the above. Show Answer Correct Answer: B) Connected to the source. 42. The phase difference between voltage and current in a purely capacitive circuit is A) 90. B) 180. C) -90. D) 0. Show Answer Correct Answer: A) 90. 43. In the case of an inductor A) Voltage leads the current by 45$^{0}$. B) Voltage lags the current by 90$^{0}$. C) Voltage leads the current by 60$^{0}$. D) Voltage leads the current by 90$^{0}$. Show Answer Correct Answer: D) Voltage leads the current by 90$^{0}$. 44. The? is the value of AC voltage that produces the same amount of power as a like value of DC voltage. A) Peak. B) Average. C) Peak to peak. D) Root mean squared. Show Answer Correct Answer: D) Root mean squared. 45. Find the Q factor of this circuit A) 35.42. B) 42.21. C) 21.74. D) 25. Show Answer Correct Answer: C) 21.74. 46. When the varying magnetic field of an inductor induces a voltage into a nearby inductor, it is called A) Mutual inductance. B) Self Inductance. C) Mutual Capacitance. D) None of the above. Show Answer Correct Answer: A) Mutual inductance. 47. What does rectification refer to in electrical terms? A) The process of converting AC to DC. B) The process of reducing current. C) The process of increasing voltage. D) The process of storing energy. Show Answer Correct Answer: A) The process of converting AC to DC. 48. An alternating current I in amps varies with time t in seconds according to the equation:I = 3 sin (50t) What is the mean power dissipated by the alternating current in a resistive load of 10 ohm? A) 810 W. B) 44 W. C) 21 W. D) 30 W. Show Answer Correct Answer: B) 44 W. 49. The power factor in a circuit with a resistance of 50$\Omega$ and an impedance of 100$\Omega$ is ..... A) 0.25. B) 0.75. C) 0.5. D) 1.0. Show Answer Correct Answer: C) 0.5. 50. What is the peak voltage in a circuit with an rms voltage of 120VAC? A) 117V. B) 120V. C) 150V. D) 170V. Show Answer Correct Answer: D) 170V. 51. What type of waveform is most commonly associated with AC? A) Triangular wave. B) Sinusoidal wave. C) Sawtooth wave. D) Square wave. Show Answer Correct Answer: B) Sinusoidal wave. 52. What is thermolysis in the context of alternating current? A) Thermolysis is the process of generating electricity using magnets. B) Thermolysis is another name for alternating current. C) Thermolysis is the conversion of AC to DC. D) Thermolysis is the measurement of current flow in a circuit. Show Answer Correct Answer: B) Thermolysis is another name for alternating current. 53. A.C. power is transmitted from a power house at a high voltage as A) It is more economical due to less power loss. B) Power cannot be transmitted at low voltages. C) A precaution against theft of transmission lines. D) The rate of transmission is faster at high voltages. Show Answer Correct Answer: A) It is more economical due to less power loss. 54. Alternating current means the current flows from negative to positive. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 55. In the UK, what is the mains frequency of the alternating current? A) 60 Hz. B) 100 Hz. C) 50 Hz. D) 120 Hz. Show Answer Correct Answer: C) 50 Hz. 56. The relationship between two alternating quantities can be represented by using A) Phasor diagram. B) Sinusoidal graph. C) Phasor diagram and sinusoidal graph. D) None of above. Show Answer Correct Answer: C) Phasor diagram and sinusoidal graph. 57. Which of the following are commonly used as rectifiers in electrical circuits? A) Anodes. B) Cathodes. C) Diodes. D) None of the above. Show Answer Correct Answer: C) Diodes. 58. Fill in the blank:Alternating current is the quickest method of hair removal, as an increased number of hairs can be treated within a short period of time when compared with the ..... method. A) Laser. B) Blend. C) Shaving. D) Waxing. Show Answer Correct Answer: B) Blend. 59. Voltage and current is an AC circuit are given by $V=5\\sin\left(100\pi t-\frac{\pi}{6}\right)$ $I=6\\sin\left(100\pi t+\frac{\pi}{6}\right)$ A) Current leads the voltage by $30^o$. B) Current leads the voltage by $60^o$. C) Voltage leads the current by $60^o$. D) Voltage leads the current by $30^o$. Show Answer Correct Answer: B) Current leads the voltage by $60^o$. 60. Average power dissipated in an ideal inductor in a.c. circuit is: A) Infinite. B) Zero. C) 100. D) One. Show Answer Correct Answer: B) Zero. ← 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 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 9 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books