This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 7 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 7 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. 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$^\circ$. 2. What does the number of cycles per second represent in alternating current? A) Voltage. B) Current. C) Frequency. D) Resistance. Show Answer Correct Answer: C) Frequency. 3. 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. 4. 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. 5. 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. 6. What is the formula for capacitive reactance? A) $\omega C$. B) $\frac{1}{\omega L}$. C) $\omega L$. D) $\frac{1}{\omega C}$. Show Answer Correct Answer: D) $\frac{1}{\omega C}$. 7. 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. 8. 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 $\sqrt{}$. 9. 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. 10. What happens when the conductor moves parallel to the lines of magnetic force? A) No emf is generated. B) The magnetic field collapses. C) Maximum emf is generated. D) The conductor heats up. Show Answer Correct Answer: A) No emf is generated. 11. What does an oscilloscope trace show for a direct current? A) The maximum potential difference. B) The frequency. C) The resistance. D) The current direction. Show Answer Correct Answer: A) The maximum potential difference. 12. 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. 13. The total resistance of the wire i A) 30 $\Omega$. B) 35 $\Omega$. C) 25 $\Omega$. D) 15 $\Omega$. Show Answer Correct Answer: D) 15 $\Omega$. 14. 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. 15. The phase difference between voltage and current in a purely capacitive circuit is A) 0. B) 90. C) -90. D) 180. Show Answer Correct Answer: B) 90. 16. In the case of an inductor A) Voltage lags the current by 90$^{0}$. B) Voltage leads the current by 90$^{0}$. C) Voltage leads the current by 60$^{0}$. D) Voltage leads the current by 45$^{0}$. Show Answer Correct Answer: B) Voltage leads the current by 90$^{0}$. 17. The? is the value of AC voltage that produces the same amount of power as a like value of DC voltage. A) Peak to peak. B) Peak. C) Average. D) Root mean squared. Show Answer Correct Answer: D) Root mean squared. 18. Find the Q factor of this circuit A) 42.21. B) 35.42. C) 21.74. D) 25. Show Answer Correct Answer: C) 21.74. 19. 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. 20. What does rectification refer to in electrical terms? A) The process of reducing current. B) The process of increasing voltage. C) The process of converting AC to DC. D) The process of storing energy. Show Answer Correct Answer: C) The process of converting AC to DC. 21. 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) 21 W. B) 30 W. C) 44 W. D) 810 W. Show Answer Correct Answer: C) 44 W. 22. The power factor in a circuit with a resistance of 50$\Omega$ and an impedance of 100$\Omega$ is ..... A) 0.5. B) 0.25. C) 0.75. D) 1.0. Show Answer Correct Answer: A) 0.5. 23. What is the peak voltage in a circuit with an rms voltage of 120VAC? A) 150V. B) 170V. C) 117V. D) 120V. Show Answer Correct Answer: B) 170V. 24. What type of waveform is most commonly associated with AC? A) Square wave. B) Triangular wave. C) Sinusoidal wave. D) Sawtooth wave. Show Answer Correct Answer: C) Sinusoidal wave. 25. What is thermolysis in the context of alternating current? A) Thermolysis is another name for alternating current. B) Thermolysis is the process of generating electricity using magnets. C) Thermolysis is the conversion of AC to DC. D) Thermolysis is the measurement of current flow in a circuit. Show Answer Correct Answer: A) Thermolysis is another name for alternating current. ← 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 8Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 9Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 10Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 11 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books