This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 22 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 22 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. What does AC smoothing mean? A) The process of inducing an emf (voltage) with a change in magnetic flux. B) Electric currents whose direction and magnitude change periodically depending on time are called alternating current. C) Steady current which delivers the same average power as the a.c. to a resistive load. D) Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor. Show Answer Correct Answer: D) Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor. 2. A 30-microfarad capacitor is in parallel with a 15-microfarad capacitor. The total capacitance is ..... A) 15. B) 30. C) 45. D) 100. Show Answer Correct Answer: C) 45. 3. What is an LCR circuit composed of? A) Inductor, Capacitor, Resistor. B) Inductor, Capacitor, Diode. C) Inductor, Resistor, Transistor. D) Capacitor, Resistor, Transistor. Show Answer Correct Answer: A) Inductor, Capacitor, Resistor. 4. The most common waveforms of ac is A) Square wave. B) Triangular wave. C) Complex wave. D) Sine wave. Show Answer Correct Answer: D) Sine wave. 5. What is the average value of current in a full-wave rectified circuit? A) Zero. B) Half the peak value. C) Equal to peak value. D) Twice the half-wave average. Show Answer Correct Answer: D) Twice the half-wave average. 6. Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct? A) For a given power level, there is a lower current. B) Lower current implies less power loss. C) Transmission lines can be made thinner. D) It is easy to reduce the voltage at the receiving end using step-down transformers. Show Answer Correct Answer: B) Lower current implies less power loss. 7. L, C and R represent physical quantities inductance, capacitance and resistance, respectively. The combination representing dimension of frequency is A) LC. B) $\left(LC\right)^{\frac{-1}{2}}$. C) $\left(\frac{L}{C}\right)^{\frac{-1}{2}}$. D) $\frac{C}{L}$. Show Answer Correct Answer: B) $\left(LC\right)^{\frac{-1}{2}}$. 8. A charged 30 micro farad capacitor is connected to a 27mH inductor. The angular frequency of free oscillations of the circuit is A) 1.1 x 10$^{3}$ rad/s. B) 2.1 x 10$^{3}$ rad/s. C) 3.1 x 10$^{3}$ rad/s. D) 4.1 x 10$^{3}$ rad/s. Show Answer Correct Answer: A) 1.1 x 10$^{3}$ rad/s. 9. The relation between the direction of induced emf and the direction of motion of the conductor is A) Parallel. B) Perpendicular. C) Equal. D) Not related. Show Answer Correct Answer: B) Perpendicular. 10. In case of phasor diagram the vector rotates A) Clockwise. B) Anticlockwise. C) Remain stationary. D) None. Show Answer Correct Answer: B) Anticlockwise. 11. What is the term for the current that does not perform any work in an A.C. circuit? A) Direct current. B) Wattless current. C) Active current. D) Reactive current. Show Answer Correct Answer: B) Wattless current. 12. If a sinusoidal wave has a frequency of 50 Hz with 30 A r.m.s current, which of the following equation represents the wave? A) 42.42 sin 314.2t. B) 60 sin 25t. C) 30 sin 50t. D) 84.84 sin 25t. Show Answer Correct Answer: A) 42.42 sin 314.2t. 13. How can phase difference be adjusted in AC circuits? A) Using only resistors. B) Phase difference can be adjusted using capacitors, inductors, variable resistors, or phase-shifting transformers. C) Adjusting the frequency of the power supply. D) Changing the voltage level of the circuit. Show Answer Correct Answer: B) Phase difference can be adjusted using capacitors, inductors, variable resistors, or phase-shifting transformers. 14. What is the effect of resistance on the Q-factor of a resonant circuit? A) Doubles Q-factor. B) Increases Q-factor. C) Decreases Q-factor. D) No effect. Show Answer Correct Answer: C) Decreases Q-factor. 15. The average value of alternating current for one complete cycle is A) Zero. B) 1. C) $\sqrt{2}$. D) None of these. Show Answer Correct Answer: A) Zero. 16. An electrical element X when connected to an alternating voltage source has current through it leading the voltage by $\pi$ A) Capacitor. B) Resistor. C) Inductor. D) Series LR ckt. Show Answer Correct Answer: A) Capacitor. 17. The induced emf in a closed coil of wire, according to Faraday's Law, is proportional to:I. The magnitude of the magnetic flux II. The magnetic flux density III. The number of turnsIV. The rate of change of magnetic flux A) I. B) II. C) II and III (. D) III and IV. E) IV. Show Answer Correct Answer: D) III and IV. 18. Why is ac current transfer more effective than dc current transfer over long distances? A) Due to the height of power lines. B) Due to the use of ac generators. C) Due to step-up and step-down transformers reducing I$^{2}$R losses. D) Due to very high voltages. Show Answer Correct Answer: C) Due to step-up and step-down transformers reducing I$^{2}$R losses. 19. What is the effect of increasing the capacitance in a capacitive AC circuit on the current? A) The current decreases. B) The current remains the same. C) The current increases. D) The current becomes zero. Show Answer Correct Answer: C) The current increases. 20. What is the phase difference in an AC circuit? A) The phase difference in an AC circuit is the angle by which the voltage and current waveforms differ, typically measured in degrees or radians. B) The phase difference is the maximum voltage in the circuit. C) The phase difference is the frequency of the AC signal. D) The phase difference is the total resistance in the circuit. Show Answer Correct Answer: A) The phase difference in an AC circuit is the angle by which the voltage and current waveforms differ, typically measured in degrees or radians. 21. What is the ratio of powers delivered by 20 V dc and 20 V peak ac to the same load? A) 20. B) 2. C) 1. D) 0.5. Show Answer Correct Answer: B) 2. 22. The power factor of LCR circuit at resonance is ..... A) 0.707. B) 1. C) Zero. D) 0.5. Show Answer Correct Answer: B) 1. 23. The above half wave form is created by an AC going into which circuit? A) Single diode. B) Transformer. C) Bridge rectifier. D) Voltage regulator. Show Answer Correct Answer: A) Single diode. 24. The waveform of alternating current/voltage is: A) Stright line. B) Curved. C) Sinusoidal. D) Cotangent. Show Answer Correct Answer: C) Sinusoidal. 25. When calculating power in a reactive or inductive AC circuit, the true power is A) More than apparent power. B) Less than the apparent power in a reactive circuit and more than the apparent power in an inductive circuit. C) Less than the apparent power. D) None of the above. Show Answer Correct Answer: C) Less than the apparent power. ← 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