This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 32 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 32 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. The mean value of current for half cycle of an ac is $\frac{10}{\pi}$ A) 0 A. B) 1 A. C) 10 A. D) 5 A. Show Answer Correct Answer: D) 5 A. 2. 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) 0.5A. B) 1A. C) 2A. D) 0.2A. Show Answer Correct Answer: D) 0.2A. 3. If the area of the plates of a capacitor is increased, the amount of capacitance ..... A) Decreases. B) Increases. C) Stays the same. D) May increase or decrease. Show Answer Correct Answer: B) Increases. 4. 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. 5. 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) Phase difference has no effect on power. C) Greater phase difference increases 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. 6. The average current/ voltage value will not be zero only if it is A) Step up. B) Rectified. C) Amplified. D) Intensified. Show Answer Correct Answer: B) Rectified. 7. 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$^\circ$. 8. 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. 9. Fill in the blank:The skin heals fairly quickly after ..... A) Treatment. B) Injury. C) Exercise. D) Exposure. Show Answer Correct Answer: A) Treatment. 10. The maximum voltage across the inductor in an ac circuit is given by A) $V_o=I_oX_L$. B) $V_o=I_{rms}X_L$. C) $V_{rms}=I_{rms}X_L$. D) $V_o=I_oL$. Show Answer Correct Answer: A) $V_o=I_oX_L$. 11. Alternating currents can be produced by a A) Dynamo. B) Choke coil. C) Transformer. D) Electric motor. Show Answer Correct Answer: A) Dynamo. 12. What type of transformer decreases the voltage from primary to secondary coil? A) Step-up Transformer. B) Step-down Transformer. C) Isolation Transformer. D) Auto Transformer. Show Answer Correct Answer: B) Step-down Transformer. 13. 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. 14. What is the phase difference between the phases in a three-phase system? A) $90^\circ$. B) $120^\circ$. C) $180^\circ$. D) $360^\circ$. Show Answer Correct Answer: B) $120^\circ$. 15. The AC value of current that has the same heating effect as that value of DC is the: A) Average. B) RMS. C) Instantaneous. D) Max. Show Answer Correct Answer: B) RMS. 16. What type of current flows through the wires in your home? A) Battery current. B) Direct current. C) Alternating current. D) Solar current. Show Answer Correct Answer: C) Alternating current. 17. 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. 18. 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. 19. What does the RMS value represent in an AC circuit? A) The peak voltage of the AC supply. B) The average voltage of the AC supply. C) The voltage value that delivers the same power as a DC supply of the same voltage. D) The minimum voltage of the AC supply. Show Answer Correct Answer: C) The voltage value that delivers the same power as a DC supply of the same voltage. 20. Phase difference between voltage and current in an AC circuit having resistor only is A) $\frac{\pi}{4}$. B) $\frac{\pi}{2}$. C) $\pi$. D) Zero. Show Answer Correct Answer: D) Zero. 21. 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) 4 A. B) 2 A. C) 6 A. D) 10 A. Show Answer Correct Answer: B) 2 A. 22. Which household appliance typically uses AC power? A) Flashlight. B) Refrigerator. C) Car battery. D) Remote control. Show Answer Correct Answer: B) Refrigerator. 23. 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) $Z=\frac{1}{\sqrt{\left(\frac{1}{R}\right)^2+\left(\frac{1}{X_L}-\frac{1}{X_C}\right)^2}}$. 24. 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) 4 L. B) 2 L. C) L/2. D) L/ 4. Show Answer Correct Answer: C) L/2. 25. What are harmonics in an AC waveform? A) Lower-frequency components. B) Higher-frequency components. C) Direct current components. D) Static components. Show Answer Correct Answer: B) Higher-frequency components. ← 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