This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 19 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 19 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. If two objects have unlike charges they will do this. A) Repel. B) Attract. C) Friction. D) Induction. Show Answer Correct Answer: B) Attract. 2. Describe the behavior of current in a capacitor when connected to an AC source. A) The current in a capacitor leads the voltage by 90 degrees when connected to an AC source. B) The current in a capacitor is constant regardless of frequency. C) The current in a capacitor lags the voltage by 90 degrees. D) The current and voltage are in phase in a capacitor. Show Answer Correct Answer: A) The current in a capacitor leads the voltage by 90 degrees when connected to an AC source. 3. What is a Direct Current? A) An electrical current flowing in many directions. B) A current with a high frequency. C) An electric current flowing in one direction only. D) A current that is never a straight line. Show Answer Correct Answer: C) An electric current flowing in one direction only. 4. In an LCR series AC circuit, if $\omega_o$ A) $\frac{\omega_oL}{C}$. B) $\left(\frac{1}{R}\right)\sqrt{\frac{L}{C}}$. C) $\frac{\omega_oC}{R}$. D) $\frac{L}{\omega_oR}$. Show Answer Correct Answer: B) $\left(\frac{1}{R}\right)\sqrt{\frac{L}{C}}$. 5. What is the time-averaged value of power in an AC circuit called? A) Peak Power. B) Instantaneous Power. C) Average Power. D) Reactive Power. Show Answer Correct Answer: C) Average Power. 6. The power factor is defined as A) Cosine of the phase difference between voltage and current. B) Ratio of resistance with impedance. C) Ratio of active power with apparent power. D) All of above. Show Answer Correct Answer: D) All of above. 7. What is the role of capacitors in AC circuits? A) Capacitors increase the voltage in AC circuits. B) Capacitors only store energy in DC circuits. C) Capacitors store and release energy, influence phase relationships, and filter signals in AC circuits. D) Capacitors are used solely for power generation in AC circuits. Show Answer Correct Answer: C) Capacitors store and release energy, influence phase relationships, and filter signals in AC circuits. 8. Which of the following is an example of direct current? A) Current in a battery-powered flashlight. B) Electricity from a power plant. C) Current in a light bulb. D) Current in a home outlet. Show Answer Correct Answer: A) Current in a battery-powered flashlight. 9. Which of the following components of an AC circuit opposes the change in current by dropping a voltage? A) Resistor. B) Inductor. C) Capacitor. D) Power source. Show Answer Correct Answer: B) Inductor. 10. An instrument that displays AC waveforms graphically is a A) Ammeter. B) Wave meter. C) Oscilloscope. D) None of the above. Show Answer Correct Answer: C) Oscilloscope. 11. The phase difference between voltage and current in a purely resistive circuit A) O. B) 90. C) -90. D) 180. Show Answer Correct Answer: A) O. 12. In AC circuit, true power depends on: A) Voltage only. B) Current only. C) Power factor. D) Frequency only. Show Answer Correct Answer: C) Power factor. 13. What are the factors that can affect the power factor of an AC circuit? A) Reactive components, harmonic distortion, and load type. B) Wire color, circuit length, and insulation type. C) Phase angle, frequency, and power rating. D) Voltage, current, and resistance. Show Answer Correct Answer: A) Reactive components, harmonic distortion, and load type. 14. When the frequency of an AC circuit is doubled, then the capacitive reactance will be ..... A) Halved. B) Doubled. C) Squared. D) Tripled. Show Answer Correct Answer: A) Halved. 15. Sharpness of Resonance is measured by A) $\frac{\omega R}{L}$. B) $\frac{\omega}{2\Lambda\omega}$. C) $\frac{2\omega}{\Lambda\omega}$. D) $\frac{\omega}{LC}$. Show Answer Correct Answer: B) $\frac{\omega}{2\Lambda\omega}$. 16. The power factor is 1 for A) Capacitive circuit. B) Inductive circuit. C) LR circuit. D) LCR circuit in resonance. Show Answer Correct Answer: D) LCR circuit in resonance. 17. What is the formula for calculating the total impedance in a series RLC circuit? A) Z = R + j(XL-XC). B) Z = R + XL + XC. C) Z = R + j(XC-XL). D) Z = R + j(XL + XC). Show Answer Correct Answer: A) Z = R + j(XL-XC). 18. What is the cosine of the phase angle in an AC circuit known as? A) Power Factor. B) Phase Difference. C) Resonance. D) Reactance. Show Answer Correct Answer: A) Power Factor. 19. The region around a magnet where the magnetic forces act is the ..... A) Magnetic field. B) Magnetic pole. C) Magnetic domain. D) Electromagnetic pole. Show Answer Correct Answer: A) Magnetic field. 20. How does a capacitor react to AC? A) As the frequency increases, the reactance decreases. B) As the frequency increases, the reactance increases. C) As the amplitude increases, the reactance increases. D) As the amplitude increases, the reactance decreases. Show Answer Correct Answer: A) As the frequency increases, the reactance decreases. 21. A family wants to reduce the risk of AC hazards in their home. Which plan would be most effective? A) Ignore damaged wires. B) Regularly check and replace faulty cords, use circuit breakers, and keep water away from outlets. C) Use more extension cords. D) Place appliances near sinks. Show Answer Correct Answer: B) Regularly check and replace faulty cords, use circuit breakers, and keep water away from outlets. 22. What is the effect of increasing resistance on the current in an R.L series circuit? A) Increasing resistance causes the current to fluctuate in an R.L series circuit. B) Increasing resistance has no effect on the current in an R.L series circuit. C) Increasing resistance increases the current in an R.L series circuit. D) Increasing resistance decreases the current in an R.L series circuit. Show Answer Correct Answer: D) Increasing resistance decreases the current in an R.L series circuit. 23. State whether the following statements is TRUE or FALSE;The various possible frequencies of electromagnetic field waves form a spectrum. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 24. The product of the source voltage and the total current is ..... A) Apparent power. B) True power. C) Reactive power. D) The power factor. Show Answer Correct Answer: A) Apparent power. 25. The unit used for capacitive reactance and inductive reactance is A) Volt. B) Ampere. C) Joule. D) Ohm. Show Answer Correct Answer: D) Ohm. ← 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