This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 4 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 4 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. What is the term for the maximum current in an A.C. circuit?(Im means peak current) A) Irms. B) Imax. C) Iav. D) Im. Show Answer Correct Answer: D) Im. 2. What is an Autotransformer? A) A transformer with a single winding. B) A transformer with no windings. C) A transformer with 2 windings. D) None of the above. Show Answer Correct Answer: A) A transformer with a single winding. 3. For the circuit with C = 15 $\mu$F connected to a 220 V, 50 Hz source, calculate the rms and peak values of current in the circuit. A) I rms = 0.71 A, i m = 1.00 A. B) I rms = 1.04 A, i m = 1.47 A. C) I rms = 2.20 A, i m = 3.11 A. D) I rms = 0.22 A, i m = 0.31 A. Show Answer Correct Answer: B) I rms = 1.04 A, i m = 1.47 A. 4. A circuit contains a AC voltage source, a resistor, and another component. The voltage amplitude is held constant as the frequency is increased. The current in the circuit is observed to increase as the frequency is increased. What is the additional component in the circuit? A) Resistor. B) Capacitor. C) Inductor. D) Light Bulb. Show Answer Correct Answer: B) Capacitor. 5. What is resonance in the context of alternating current? A) Resonance happens when the circuit has only capacitive reactance. B) Resonance is when the circuit has no resistance. C) Resonance in the context of alternating current is when inductive and capacitive reactances cancel each other out, resulting in a purely resistive circuit. D) Resonance occurs when the circuit has only inductive reactance. Show Answer Correct Answer: C) Resonance in the context of alternating current is when inductive and capacitive reactances cancel each other out, resulting in a purely resistive circuit. 6. Fill in the blank:It is ineffective when treating distorted curved hair follicles compared to the ..... methods. A) Blend. B) Laser. C) Thermal. D) Flash. Show Answer Correct Answer: A) Blend. 7. The instantaneous voltage through a device of impedance 20ohm is e = 80 sin 100 $\pi$ A) 3 A. B) 2.828 A. C) 1.732 A. D) 4A. Show Answer Correct Answer: B) 2.828 A. 8. What is the phase difference between the current and voltage in a purely resistive AC circuit? A) 0$^\circ$. B) 45$^\circ$. C) 90$^\circ$. D) 180$^\circ$. Show Answer Correct Answer: A) 0$^\circ$. 9. With the help of a phasor diagram, find the impedance of a series LCR circuit. A) Z = R + (X L-X C). B) Z = $\sqrt{R^2 + (X_L-X_C)^2}$. C) Z = $\sqrt{X_L^2 + X_C^2}$. D) Z = $\sqrt{R^2 + X_L^2 + X_C^2}$. Show Answer Correct Answer: B) Z = $\sqrt{R^2 + (X_L-X_C)^2}$. 10. The frequency of ac generator depends on A) Speed of rotation of coil. B) Amplitude of ac. C) Size of coil. D) All the above. Show Answer Correct Answer: A) Speed of rotation of coil. 11. What is the significance of phase difference in AC circuits? A) Phase difference only affects the frequency of the circuit. B) The significance of phase difference in AC circuits is to determine the power factor and efficiency of power transfer. C) Phase difference determines the color of the circuit components. D) Phase difference is irrelevant in resistive circuits. Show Answer Correct Answer: B) The significance of phase difference in AC circuits is to determine the power factor and efficiency of power transfer. 12. A pure capacitor is connected to an a.c. supply of frequency 50 Hz and r.m.s. voltage 6.0 V. If the r.m.s. value of the current in the circuit is 30 mA, what is the capacitance of the capacitor? A) 13 $\mu$. B) 14 $\mu$. C) 15 $\mu$. D) 16 $\mu$. Show Answer Correct Answer: D) 16 $\mu$. 13. What is the typical voltage of a single-phase AC supply in Great Britain? A) 110 V. B) 230 V. C) 400 V. D) 600 V. Show Answer Correct Answer: B) 230 V. 14. What is the main hazard associated with AC electricity in homes? A) Overheating. B) Electric shock. C) Rusting. D) Noise pollution. Show Answer Correct Answer: B) Electric shock. 15. You notice that a circuit breaker keeps tripping when you use a certain appliance. What is the most likely reason? A) The appliance is using too little current. B) The appliance is causing an overload or short circuit. C) The appliance is not plugged in. D) The appliance is using DC power. Show Answer Correct Answer: B) The appliance is causing an overload or short circuit. 16. The number of turns in a long solenoid is doubled; how does the inductance of the solenoid change? A) It doesn't change. B) It doubles. C) It quadruples. D) It is cut to a half. E) It is cut to a quarter. Show Answer Correct Answer: C) It quadruples. 17. Which of the following is a use of AC in homes? A) Powering LED flashlights. B) Running washing machines. C) Charging car batteries. D) Operating calculators. Show Answer Correct Answer: B) Running washing machines. 18. Power factor is maximum in an LCR series circuit when A) X$_{L}$=X$_{C}$. B) R=0. C) X$_{L}$ =0. D) X$_{C}$ =0. Show Answer Correct Answer: A) X$_{L}$=X$_{C}$. 19. What is the impedance in an AC circuit and how is it calculated? A) Impedance is calculated as Z = R-jX. B) Impedance is the total power consumed in a circuit. C) Impedance is only the resistance in a circuit. D) Impedance (Z) is calculated as Z = R + jX, where R is resistance and X is reactance. Show Answer Correct Answer: D) Impedance (Z) is calculated as Z = R + jX, where R is resistance and X is reactance. 20. Two advantages of AC over DC are: A) Easy to generate, easy to change voltage and current values. B) A comes before D in the alphabet. C) Don't know because I did not study this. D) None of the above. Show Answer Correct Answer: A) Easy to generate, easy to change voltage and current values. 21. What is the primary disadvantage of A.C.? A) Lower efficiency. B) Higher danger level. C) More complex circuitry. D) Higher cost. Show Answer Correct Answer: B) Higher danger level. 22. What is the SI unit for capacitive reactance? A) Farad. B) Mho. C) Ohm. D) Cordel. Show Answer Correct Answer: C) Ohm. 23. The Phase angle between Current and Voltage in a LCR circuit is given by A) Arctan (XL-XC / R). B) Tan (XL-XC/R). C) Arctan (XC-XL/R). D) Tan (XC-XL/R). Show Answer Correct Answer: C) Arctan (XC-XL/R). 24. What is the effect of placing a capacitor in parallel with a resistive load? A) It increases the resistance. B) It smooths the rectified voltage. C) It decreases the voltage. D) It increases the frequency. Show Answer Correct Answer: B) It smooths the rectified voltage. 25. Find the power suppled by the electric plant, if the power loss is negligible A) 1400 kW. B) 500 kW. C) 1600 kW. D) 600 kW. Show Answer Correct Answer: A) 1400 kW. ← 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 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 10Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 11 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books