This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 9 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 9 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. If the vector diagram of two AC waveforms is a right angle, then the waves ..... A) Are in phase. B) Are 90$^\circ$ out of phase. C) Have the same frequency. D) Have the same peak voltage. Show Answer Correct Answer: B) Are 90$^\circ$ out of phase. 2. In a pure inductive circuit, the phase angle between current and emf. A) 120$^\circ$. B) 90$^\circ$. C) 45$^\circ$. D) 60$^\circ$. Show Answer Correct Answer: B) 90$^\circ$. 3. The term that describes the combined resistive forces in an ac circuit is A) Resistance. B) Reactance. C) Impedance. D) None of the above. Show Answer Correct Answer: C) Impedance. 4. Explain the concept of impedance in AC circuits. A) Impedance is the measure of voltage in a circuit. B) Impedance is the total opposition to AC current flow in a circuit, combining resistance and reactance. C) Impedance is the speed of current flow in a circuit. D) Impedance is only the resistance in a circuit. Show Answer Correct Answer: B) Impedance is the total opposition to AC current flow in a circuit, combining resistance and reactance. 5. High frequency oscillations refer to the frequency of the wave length and the number of cycles completed per second. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 6. On the oscilloscope the time is represented on A) The vertical axis. B) The horizontal axis. C) The sine of the angle. D) Not represented on the scope. Show Answer Correct Answer: B) The horizontal axis. 7. Condition for resonance A) XL =1/XC. B) XL = 2XC. C) XL = XC. D) XC = 1/XL. Show Answer Correct Answer: C) XL = XC. 8. In LCR series ac circuit, the current A) Is always in phase with the voltage. B) Always lags the generator voltage. C) Always leads the generator voltage. D) None of these. Show Answer Correct Answer: D) None of these. 9. Milli Amps equals A) 1000 A. B) 10 A. C) 0.1 A. D) 0.001 A. Show Answer Correct Answer: D) 0.001 A. 10. Find the correct relationship from the phasor diagram A) VL > VC. B) VL < VC. C) VL = VC. D) VL $\geq$ VC. Show Answer Correct Answer: A) VL > VC. 11. In the case of phasor diagram, the vector rotates A) Clockwise. B) Anti-clockwise. C) Remain stationary. D) None. Show Answer Correct Answer: B) Anti-clockwise. 12. When capacitors are connected in parallel, the total capacitance is equal to A) The sum of the reciprocals of the capacitances. B) The sum of the capacitances divided by the number of capacitors. C) The sum of the capacitances. D) None of the above. Show Answer Correct Answer: C) The sum of the capacitances. 13. A transformer is used to light a 100 W and 100 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately A) 30%. B) 50%. C) 90%. D) 10%. Show Answer Correct Answer: C) 90%. 14. Which type of current is used in batteries A) Alternating Current (AC). B) Direct Current (DC). C) All the above. D) None of the above. Show Answer Correct Answer: B) Direct Current (DC). 15. What is the difference between series and parallel resonance? A) Parallel resonance results in maximum current flow. B) The main difference is that series resonance maximizes current while parallel resonance maximizes voltage. C) Series resonance and parallel resonance have the same effect on circuit behavior. D) Series resonance is used for high voltage applications. Show Answer Correct Answer: B) The main difference is that series resonance maximizes current while parallel resonance maximizes voltage. 16. Poor power factor A) Reduces load handling capability of electrical system. B) Results in more power losses in electrical system. C) Results in less power losses in electrical system. D) Overloads the power supply. Show Answer Correct Answer: B) Results in more power losses in electrical system. 17. What is the relationship between RMS current and peak current? A) Irms = Imax x 0.5. B) Irms = Imax x 0.707. C) Irms = Imax x 1.414. D) Irms = Imax x 2. Show Answer Correct Answer: B) Irms = Imax x 0.707. 18. What does AC stand for in electrical terms? A) Active Current. B) Alternating Current. C) Absolute Current. D) Applied Current. Show Answer Correct Answer: B) Alternating Current. 19. How much inductance should be connected to 100V, 50Hz AC supply so that a maximum current of 0.45A flows through it A) 5 H. B) 15 H. C) 1 H. D) 10 H. Show Answer Correct Answer: C) 1 H. 20. The electricity in our house is A) AC. B) DC. C) BC. D) AD. Show Answer Correct Answer: A) AC. 21. What is the purpose of a rectifier in an AC system? A) To amplify the AC signal. B) To filter out noise from the AC signal. C) To store energy in the AC system. D) The purpose of a rectifier in an AC system is to convert AC to DC. Show Answer Correct Answer: D) The purpose of a rectifier in an AC system is to convert AC to DC. 22. The instantaneous current in an ac circuit is i=2.0 sin314t, what is rms value of the current. A) 1.414 A. B) 2.828A. C) 1 A. D) 2 A. Show Answer Correct Answer: A) 1.414 A. 23. X-ray photographs show softer tissue A) As invisible. B) As dark, highly exposed areas. C) The same as dense bones. D) As bright white areas. Show Answer Correct Answer: B) As dark, highly exposed areas. 24. What is the opposition to AC by a capacitor called? A) Inductive Reactance. B) Capacitive Reactance. C) Impedance. D) Resistance. Show Answer Correct Answer: B) Capacitive Reactance. 25. Power dissipation in pure inductive or in a pure capacitive circuit is: A) Infinite. B) Zero. C) Minimum. D) Maximum. Show Answer Correct Answer: B) Zero. ← 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 10Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 11 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books