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 13 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 13 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. In a pure inductor circuit, ..... A) The current and voltage are in antiphase. B) The voltage leads current by $\frac{\pi}{2}$. C) The current leads voltage by $\frac{\pi}{2}$. D) The current and voltage are in phase. Show Answer Correct Answer: B) The voltage leads current by $\frac{\pi}{2}$. 2. What is the term for the difference between half power points in a resonance curve? A) Impedance. B) Bandwidth. C) Reactance. D) Q-factor. Show Answer Correct Answer: B) Bandwidth. 3. What will happen, if we connect capacitor to DC Supply. A) It allows DC. B) It blocks DC. C) T rectifies. D) None of these. E) Hint:Diode is unidirectional and uncontrolled device. In rectifier circuit, diode use as a switch to convert ac to dc for rectification purpose. Show Answer Correct Answer: B) It blocks DC. 4. Cauterisation uses a high intensity, high frequency current which is absorbed by the skin tissues and leads to the water molecules within the tissues being vapourised, drying out the tissues by ..... ? A) Electrolysis. B) Electro-fulguration. C) Electro-desiccation. D) Electro-coagulation. Show Answer Correct Answer: C) Electro-desiccation. 5. Alternating current differs from direct current because ..... A) It alternates from AC to DC. B) The current alternates between 2 A and 5 A. C) It changes direction. D) The resistance fluctuates back and forth. Show Answer Correct Answer: C) It changes direction. 6. What is the principle of the transformer? A) Coulomb's law. B) Mutual induction. C) Ampere's law. D) Gauss law. Show Answer Correct Answer: B) Mutual induction. 7. A student is comparing AC and DC for use in household appliances. What evidence supports the use of AC for most appliances? A) AC is more expensive to generate. B) AC can be easily transformed to different voltages and is compatible with the power grid. C) DC is more common in homes. D) DC is safer for all appliances. Show Answer Correct Answer: B) AC can be easily transformed to different voltages and is compatible with the power grid. 8. What is the primary use of choke coils in A.C. circuits? A) Increase voltage. B) Increase current. C) Reduce current without power loss. D) Store energy. Show Answer Correct Answer: C) Reduce current without power loss. 9. Fill in the blank:There is a higher level of regrowth compared with the blend or ..... methods. A) Galvanic. B) Laser. C) Threading. D) Waxing. Show Answer Correct Answer: A) Galvanic. 10. A capacitor acts as an infinite resistance for A) AC. B) DC. C) Both AC and DC. D) Neither AC nor DC. Show Answer Correct Answer: B) DC. 11. Which of the following can provide direct current besides batteries? A) Solar cells. B) Light bulbs. C) Outlets. D) Power plants. Show Answer Correct Answer: A) Solar cells. 12. Complete the sentence:The peak potential difference of the UK mains supply is ..... A) 230 V. B) 260 V. C) 240 V. D) 250 V. Show Answer Correct Answer: C) 240 V. 13. What is the process to reduce the range of the output voltage/current, but does not fall to zero? A) Oscillation. B) Amplification. C) Rectification. D) Smoothing. Show Answer Correct Answer: D) Smoothing. 14. Which of the following does NOT depend on frequency? A) Inductive reactance. B) Resistance. C) Impedance. D) Capacitive reactance. Show Answer Correct Answer: B) Resistance. 15. Radio exploits which property of Alternating Currents? A) Sinusoidally Varying Nature. B) Higher Current compared to Direct Current. C) Resonance property of RC circuit. D) Resonance property of LCR circuit. Show Answer Correct Answer: D) Resonance property of LCR circuit. 16. In AC circuit resonance will take place when induced reactance is A) One third of the capacitive reactance. B) Double the capacitive reactance. C) Half the capacitive reactance. D) Equal to the capacitive reactance. Show Answer Correct Answer: D) Equal to the capacitive reactance. 17. Pada suatu rangkaian AC terdiri atas resistor 15 $\Omega$, induktor 6 $\Omega$, dan kapasitor 26 $\Omega$. Impedansi totalnya rangkaian tersebut adalah ..... A) 25 $\Omega$. B) 17 $\Omega$. C) 18 $\Omega$. D) 13 $\Omega$. E) 20 $\Omega$. Show Answer Correct Answer: A) 25 $\Omega$. 18. What condition occurs when the inductive reactance equals the capacitive reactance? A) Reactance. B) Dissonance. C) Impedance. D) Resonance. Show Answer Correct Answer: D) Resonance. 19. Coagulation uses a lower intensity of high frequency current. What does this cause? A) Coagulation of the protein within the molecules of the tissues and blood vessels. B) Cooling of the skin. C) Increased hair growth. D) Decreased blood flow. Show Answer Correct Answer: A) Coagulation of the protein within the molecules of the tissues and blood vessels. 20. What causes the movement of electrons in a Direct Current? A) Pulsed electrons on a wire. B) The alternating push of electrons along the wire. C) The steady pull of electrons along the wire. D) None of the above. Show Answer Correct Answer: C) The steady pull of electrons along the wire. 21. A battery makes ..... A) Alternating current. B) Direct current. C) All the above. D) None of the above. Show Answer Correct Answer: B) Direct current. 22. Current that is used by most household appliances A) AC. B) AC/DC. C) DC. D) BC. Show Answer Correct Answer: A) AC. 23. The total capacitance of two 15$\mu$F capacitors connected in parallel is ..... A) 5$\mu$F. B) 30$\mu$F. C) 15$\mu$F. D) 10$\mu$F. Show Answer Correct Answer: B) 30$\mu$F. 24. Power companies supply ac, not dc, because: A) The power station generates AC and not DC because the transmission of alternating current is easier and very efficient. B) There is no longer a need for dc. C) Dc is more dangerous. D) There are not enough batteries. Show Answer Correct Answer: A) The power station generates AC and not DC because the transmission of alternating current is easier and very efficient. 25. The transformer voltage induced in the secondary coil of a transformer is mainly due to A) Iron core of the transformer. B) Varying magnetic field. C) Vibrations of the primary coil. D) Varying electric field. Show Answer Correct Answer: B) Varying magnetic field. 26. What is the Q-factor in resonance? A) Power factor. B) Ratio of resonant frequency to bandwidth. C) Ratio of bandwidth to resonant frequency. D) Voltage ratio. Show Answer Correct Answer: B) Ratio of resonant frequency to bandwidth. 27. Describe the impact of impedance mismatch in an AC circuit. A) Elimination of signal reflections. B) Improved waveform distortion. C) The impact of impedance mismatch in an AC circuit includes signal reflections, reduced power transfer efficiency, and waveform distortion. D) Increased power transfer efficiency. Show Answer Correct Answer: C) The impact of impedance mismatch in an AC circuit includes signal reflections, reduced power transfer efficiency, and waveform distortion. 28. What is the phase angle in a sinusoidal AC waveform? A) The phase angle is the frequency of the waveform. B) The phase angle is the duration of one complete cycle. C) The phase angle is the amplitude of the waveform. D) The phase angle is the measure of the phase difference between the waveform and a reference point, expressed in degrees or radians. Show Answer Correct Answer: D) The phase angle is the measure of the phase difference between the waveform and a reference point, expressed in degrees or radians. 29. In a LCR circuit having L = 8.0 henry, C = 0.5 mF and R = 100 ohm in series. The resonance frequency in per second is A) 600 Hz. B) 500 Hz. C) 600 radian. D) 500 radian. Show Answer Correct Answer: D) 500 radian. 30. What is required for emf to be generated in a conductor? A) There must be relative motion between a conductor and a magnetic field. B) The magnetic field must be stationary. C) The conductor must be insulated. D) The conductor must be stationary. Show Answer Correct Answer: A) There must be relative motion between a conductor and a magnetic field. 31. What are the advantages of using AC over DC for power distribution? A) AC can be easily transformed to different voltages, allowing for efficient long-distance transmission and lower energy losses. B) AC is more dangerous than DC for household use. C) AC requires more maintenance than DC systems. D) DC can be easily transformed to different voltages. Show Answer Correct Answer: A) AC can be easily transformed to different voltages, allowing for efficient long-distance transmission and lower energy losses. 32. The mean value of current for half cycle of an ac is $\frac{10}{\pi}$ A) 0 A. B) 10 A. C) 1 A. D) 5 A. Show Answer Correct Answer: D) 5 A. 33. A series RLC circuit has a resistance of 10.0 $\Omega$ and a impedance of 50.0 $\Omega$. If the rms voltage applied to the circuit is 10 V, what rms current? A) 2A. B) 1A. C) 0.2A. D) 0.5A. Show Answer Correct Answer: C) 0.2A. 34. If the area of the plates of a capacitor is increased, the amount of capacitance ..... A) Increases. B) May increase or decrease. C) Stays the same. D) Decreases. Show Answer Correct Answer: A) Increases. 35. The current in an inductive circuit ..... A) Is faster than the voltage. B) Is the same as the voltage. C) Lags the voltage. D) Counteracts the voltage. Show Answer Correct Answer: C) Lags the voltage. 36. What is the effect of phase difference on power in AC circuits? A) The phase difference affects the real power; greater phase difference reduces power. B) Greater phase difference increases power. C) Phase difference has no effect on power. D) Power is constant regardless of phase difference. Show Answer Correct Answer: A) The phase difference affects the real power; greater phase difference reduces power. 37. The average current/ voltage value will not be zero only if it is A) Step up. B) Amplified. C) Rectified. D) Intensified. Show Answer Correct Answer: C) Rectified. 38. What is the relationship between the angle of the conductor and the emf generated? A) Emf is constant at all angles. B) Emf is maximum at 90$^\circ$ and 270$^\circ$. C) Emf is maximum at 0$^\circ$ and 180$^\circ$. D) The angle has no relationship. Show Answer Correct Answer: C) Emf is maximum at 0$^\circ$ and 180$^\circ$. 39. Explain the significance of the frequency in an AC circuit. A) Frequency has no effect on AC circuits. B) Higher frequency always reduces power consumption. C) Frequency only affects DC circuits. D) Frequency is significant in an AC circuit as it influences impedance, reactive component behavior, and overall power consumption. Show Answer Correct Answer: D) Frequency is significant in an AC circuit as it influences impedance, reactive component behavior, and overall power consumption. 40. Fill in the blank:The skin heals fairly quickly after ..... A) Exercise. B) Exposure. C) Injury. D) Treatment. Show Answer Correct Answer: D) Treatment. 41. The maximum voltage across the inductor in an ac circuit is given by A) $V_o=I_oL$. B) $V_o=I_{rms}X_L$. C) $V_o=I_oX_L$. D) $V_{rms}=I_{rms}X_L$. Show Answer Correct Answer: C) $V_o=I_oX_L$. 42. Alternating currents can be produced by a A) Choke coil. B) Electric motor. C) Dynamo. D) Transformer. Show Answer Correct Answer: C) Dynamo. 43. What type of transformer decreases the voltage from primary to secondary coil? A) Step-up Transformer. B) Isolation Transformer. C) Auto Transformer. D) Step-down Transformer. Show Answer Correct Answer: D) Step-down Transformer. 44. Unless otherwise specigied, any values given for current or voltage in an AC circuit are assumed to be A) Instantaneous values. B) Effective values. C) Maximum values. D) None of the above. Show Answer Correct Answer: B) Effective values. 45. What is the phase difference between the phases in a three-phase system? A) $120^\circ$. B) $90^\circ$. C) $180^\circ$. D) $360^\circ$. Show Answer Correct Answer: A) $120^\circ$. 46. The AC value of current that has the same heating effect as that value of DC is the: A) Instantaneous. B) RMS. C) Average. D) Max. Show Answer Correct Answer: B) RMS. 47. What type of current flows through the wires in your home? A) Direct current. B) Battery current. C) Alternating current. D) Solar current. Show Answer Correct Answer: C) Alternating current. 48. In a pure resistance 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: C) Both current and voltage are in phase. 49. The working voltage in an ac circuit should be A) Equal to the highest applied voltage. B) At least 20 percent greater than the highest applied voltage. C) At least 50 percent greater than the highest applied voltage. D) None of the above. Show Answer Correct Answer: C) At least 50 percent greater than the highest applied voltage. 50. What does the RMS value represent in an AC circuit? A) The voltage value that delivers the same power as a DC supply of the same voltage. B) The average voltage of the AC supply. C) The peak voltage of the AC supply. D) The minimum voltage of the AC supply. Show Answer Correct Answer: A) The voltage value that delivers the same power as a DC supply of the same voltage. 51. Phase difference between voltage and current in an AC circuit having resistor only is A) $\frac{\pi}{2}$. B) $\frac{\pi}{4}$. C) Zero. D) $\pi$. Show Answer Correct Answer: C) Zero. 52. In an ideal transformer, number of turns in the primary are 140 and that in the secondary are 280. If current in primary is 4A, then that in the secondary is A) 6 A. B) 10 A. C) 2 A. D) 4 A. Show Answer Correct Answer: C) 2 A. 53. Which household appliance typically uses AC power? A) Refrigerator. B) Car battery. C) Flashlight. D) Remote control. Show Answer Correct Answer: A) Refrigerator. 54. What is the formula for parallel impedance in an RLC circuit? A) $Z=R+\left(X_L+X_C\right)$. B) $Z=\frac{1}{\sqrt{\left(\frac{1}{R}\right)^2+\left(\frac{1}{X_L}-\frac{1}{X_C}\right)^2}}$. C) $Z=R^2+\left(X_L-X_C\right)^2$. D) None of the above. Show Answer Correct Answer: B) $Z=\frac{1}{\sqrt{\left(\frac{1}{R}\right)^2+\left(\frac{1}{X_L}-\frac{1}{X_C}\right)^2}}$. 55. In an LCR circuit, capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to ..... A) 2 L. B) 4 L. C) L/2. D) L/ 4. Show Answer Correct Answer: C) L/2. 56. What are harmonics in an AC waveform? A) Lower-frequency components. B) Static components. C) Higher-frequency components. D) Direct current components. Show Answer Correct Answer: C) Higher-frequency components. 57. Which of the following is a benefit of using AC for power distribution in cities? A) AC is less affected by electromagnetic interference. B) AC allows for easy voltage transformation to meet different needs. C) AC is more stable in extreme weather conditions. D) AC requires less infrastructure. Show Answer Correct Answer: B) AC allows for easy voltage transformation to meet different needs. 58. What is the mean power dissipated in a resistor connected to an alternating voltage? A) The product of peak voltage and peak current. B) The product of r.m.s. voltage and r.m.s. current. C) The sum of all power values over a cycle. D) The average of instantaneous power. Show Answer Correct Answer: B) The product of r.m.s. voltage and r.m.s. current. 59. What is the true power in a 2A series RL circuit with a 100$\Omega$ resistor? A) 600W. B) 400W. C) 200W. D) 50W. Show Answer Correct Answer: B) 400W. 60. A heater is rated as 230 V, 10 kW. The value 230 V refers to A) Average voltage. B) Peal voltage. C) R.m.s voltage. D) None of the above. Show Answer Correct Answer: C) R.m.s voltage. ← 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