This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 15 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 15 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. A step-up transformer connected to a 220 V ac line is to supply 22 kV for a neon sign in secondary circuit. In primary circuit, a fuse wire is connected which is to blow when the current in the secondary circuit exceeds 10 mA. The turn ratio of the transformer is A) 50. B) 100. C) 150. D) 200. Show Answer Correct Answer: B) 100. 2. If the current changes from 20A to 10A in 5 seconds and the value of inductance is 1H, calculate the emf induced. A) 8V. B) 6V. C) 4V. D) 2V. Show Answer Correct Answer: D) 2V. 3. What is the maximum phase difference possible in an AC circuit? A) 360 degrees. B) 180 degrees. C) 270 degrees. D) 90 degrees. Show Answer Correct Answer: B) 180 degrees. 4. The formula for calculating the RMS value of a waveform is A) Vrms=.707*Vpeak. B) Vrms=1.414*Vpeak. C) All the above. D) None of the above. Show Answer Correct Answer: A) Vrms=.707*Vpeak. 5. A transformer with 10 turns in the primary and two turns in the secondary has a turns ratio of ..... A) 8:1. B) 10:1. C) 20:1. D) 5:1. Show Answer Correct Answer: D) 5:1. 6. How does a transformer work in an AC circuit? A) A transformer converts DC to AC voltage directly. B) A transformer transfers electrical energy between two or more circuits through electromagnetic induction in an AC circuit. C) A transformer generates electricity using solar power. D) A transformer stores electrical energy in batteries. Show Answer Correct Answer: B) A transformer transfers electrical energy between two or more circuits through electromagnetic induction in an AC circuit. 7. What is the best method of treating the lower hair follicle to render the follicle inactive or weaken its ability to reproduce new hair growth? A) Using thermal heat or damage to the germinative tissue through short wave diathermy (electro-coagulation). B) Applying topical creams to the surface of the skin. C) Massaging the area with essential oils. D) Exposing the follicle to ultraviolet light therapy. Show Answer Correct Answer: A) Using thermal heat or damage to the germinative tissue through short wave diathermy (electro-coagulation). 8. The value of current in the circuit is A) 14 A. B) 5 A. C) 9.46 A. D) 6.28 A. Show Answer Correct Answer: C) 9.46 A. 9. AC generator is used to A) Convert low voltage into high voltage. B) High voltage into low voltage. C) Mechanical energy into electrical energy. D) All of the above. Show Answer Correct Answer: C) Mechanical energy into electrical energy. 10. Battery is A) AC source. B) DC source. C) None of the above. D) All of the above. Show Answer Correct Answer: B) DC source. 11. Disadvantages of DC are A) High cost when dealing with high current systems; i.e. larger cables, fuses, switches and other components required for high current, low voltage applications. B) Difficult to obtain DC appliances and equipment. C) Higher chances of fire hazards when maximum circuit ratings and wire sizes are not strictly adhered to. D) All the above. Show Answer Correct Answer: D) All the above. 12. At what voltage is electricity typically supplied to domestic users in the UK? A) 230V. B) 110V. C) 400V. D) 500V. Show Answer Correct Answer: A) 230V. 13. The power factor of a good choke coil is ..... A) Nearly zero. B) Exactly zero. C) Nearly one. D) Exactly one. Show Answer Correct Answer: A) Nearly zero. 14. What happens to the temperature rise in a resistor when 1 amp of AC current passes through it compared to 1 amp of DC current? A) The temperature rise is higher with AC current. B) The temperature rise is lower with AC current. C) The temperature rise is the same for both AC and DC current. D) The temperature rise is zero with AC current. Show Answer Correct Answer: B) The temperature rise is lower with AC current. 15. Power factor of a purely inductive circuit is: A) 1. B) 0. C) -1. D) 0.5. Show Answer Correct Answer: B) 0. 16. A 15 $\mu$F capacitor is connected to a 220 V, 50 Hz source . Determine the capacitive reactance. A) 15 $\Omega$. B) 50 $\Omega$. C) 212 $\Omega$. D) 440 $\Omega$. Show Answer Correct Answer: C) 212 $\Omega$. 17. What is a type of electric current that reverses direction periodically over time? A) Direct currents. B) Alternating currents. C) All the above. D) None of the above. Show Answer Correct Answer: B) Alternating currents. 18. The instantaneous current in an ac circuit is i=2.0 sin 314t, what is its frequency? A) 100 Hz. B) 75 Hz. C) 60 Hz. D) 50 Hz. Show Answer Correct Answer: D) 50 Hz. 19. Explain the concept of resonance in an R.L.C series AC circuit. A) Resonance in an R.L.C series AC circuit is the condition where inductive and capacitive reactances are equal, resulting in maximum current at the resonant frequency. B) Resonance happens at any frequency regardless of reactance values. C) Resonance is achieved when the resistance is minimized in the circuit. D) Resonance occurs when the circuit is disconnected from the power source. Show Answer Correct Answer: A) Resonance in an R.L.C series AC circuit is the condition where inductive and capacitive reactances are equal, resulting in maximum current at the resonant frequency. 20. Which of these will cause the resistance of a conductor to decrease? A) Decrease the length of the cross-sectional area. B) Decrease the length or increase the cross-sectional area. C) Increase the length or decrease the cross-sectional area. D) None of the above. Show Answer Correct Answer: B) Decrease the length or increase the cross-sectional area. 21. A coil has L= 0.04 H and R = 12 $\Omega$ when it is connected to 220 V. 50 Hz supply the current flowing through the coil, in amperes is A) 10.7. B) 11.7. C) 14.7. D) 12.7. Show Answer Correct Answer: D) 12.7. 22. Which of the following is NOT a common AC household component? A) Light bulb. B) Electric fan. C) Television. D) Car engine. Show Answer Correct Answer: D) Car engine. 23. How can the frequency of an alternating current be calculated using an oscilloscope trace? A) By measuring the time between two peaks. B) By measuring the height of the peak. C) By measuring the resistance of the circuit. D) By measuring the current direction. Show Answer Correct Answer: A) By measuring the time between two peaks. 24. In AC generator, maximum emf generated at an angle of A) 0 and 90. B) 90 and 180. C) 90 and 270. D) 180 and 360. Show Answer Correct Answer: C) 90 and 270. 25. The opposition of an inductor to the alternating current flow is known as A) Inductive reactant. B) Capacitive reactant. C) Resistance. D) None of the above. Show Answer Correct Answer: A) Inductive reactant. ← 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