This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 18 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 18 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. How many times per second does alternating current change direction? A) 30 times. B) 60 times. C) 90 times. D) 120 times. Show Answer Correct Answer: B) 60 times. 2. Which of the following statements about a series RCL circuit is true? A) At resonance, the total reactance and total resistance are equal. B) The impedance at resonance is purely inductive. C) The current flowing in the circuit at resonance is at maximum. D) The impedance at resonance is at maximum. Show Answer Correct Answer: C) The current flowing in the circuit at resonance is at maximum. 3. In alternating current equation, $I=I_o\\sin\\omega t$ $I_o$ A) Instantaneous current. B) Lowest current. C) RMS current. D) Peak current. Show Answer Correct Answer: D) Peak current. 4. What is the reactance for inductor? A) WL. B) WC. C) 1/wL. D) 1/wC. Show Answer Correct Answer: A) WL. 5. Diodes are used in electrical power supply circuits primarily as A) Switches. B) Rectifiers. C) Relays. D) None of the above. Show Answer Correct Answer: B) Rectifiers. 6. If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor A) Increases to 4 times its original value. B) Increases to twice its original value. C) Decreases to one-half its original value. D) Decreases to one-fourth its original value. Show Answer Correct Answer: B) Increases to twice its original value. 7. . For unity power factor the circuit should be A) Purely capacitive. B) Purely resistive. C) LCR series circuit. D) Purely inductive. Show Answer Correct Answer: B) Purely resistive. 8. Peak to Peak voltage equals A) 2*Amplitude. B) 2*Vmax. C) 2*Vp. D) All of the above. Show Answer Correct Answer: D) All of the above. 9. At resonance, which of the physical quantity(s) is/are maximum? A) Current. B) Impedance. C) Both a and b. D) None of these. Show Answer Correct Answer: A) Current. 10. What is the phase difference between voltage and current in an alternating current circuit if the inductive reactance is 26 Ohm, the capasitive reactance is 20 Ohm and the active resistance is 8 Ohm? A) 53$^{0}$. B) 25$^{0}$. C) 120$^{0}$. D) 67$^{0}$. Show Answer Correct Answer: A) 53$^{0}$. 11. As frequency of an ac circuit increases, the current first increases and then decreases. What combination of circuit elements is most likely to comprise the circuit? A) Inductor and capacitor. B) Resistor and inductor. C) Resistor and capacitor. D) Resistor, inductor and capacitor. Show Answer Correct Answer: A) Inductor and capacitor. 12. What type of current more efficiently provides energy further distances? A) Alternating currents. B) Direct currents. C) Pulsating currents. D) Variable currents. Show Answer Correct Answer: A) Alternating currents. 13. How does the power factor affect AC circuits? A) The power factor affects the efficiency and performance of AC circuits by indicating how effectively the electrical power is being converted into useful work. B) The power factor only affects DC circuits. C) A higher power factor always leads to higher voltage. D) The power factor has no impact on AC circuits. Show Answer Correct Answer: A) The power factor affects the efficiency and performance of AC circuits by indicating how effectively the electrical power is being converted into useful work. 14. Transformer works on the principle of A) Total internal reflection. B) Converter. C) Inverter. D) Mutual induction. Show Answer Correct Answer: D) Mutual induction. 15. Why is AC more efficient for power transmission over long distances compared to DC? A) AC requires less maintenance. B) AC can be transmitted at higher voltages, reducing current and energy losses. C) AC is less affected by weather conditions. D) AC cables are cheaper to manufacture. Show Answer Correct Answer: B) AC can be transmitted at higher voltages, reducing current and energy losses. 16. Explain the significance of power factor in AC circuits. A) Power factor in AC circuits is significant as it indicates how effectively electrical power is being converted into useful work. A higher power factor means more efficient power usage. B) Power factor only affects DC circuits. C) Power factor has no impact on electrical efficiency. D) Power factor is a measure of voltage stability. Show Answer Correct Answer: A) Power factor in AC circuits is significant as it indicates how effectively electrical power is being converted into useful work. A higher power factor means more efficient power usage. 17. What is the primary reason AC is used in household power supply? A) AC is cheaper to produce. B) AC can be easily transformed to the required voltage levels. C) AC is safer than DC. D) AC is more environmentally friendly. Show Answer Correct Answer: B) AC can be easily transformed to the required voltage levels. 18. A 100 turn coil of area 0.1m$^{2}$ rotates at half a revolution per second. It is placed in a magnetic field of 0.01T perpendicular to the axis of the coil. Calculate the maximum voltage generated in the coil. A) 0.314V. B) 314V. C) 31.4V. D) 3.14V. Show Answer Correct Answer: A) 0.314V. 19. The total capacitance of two 15$\mu$F capacitors connected in series is ..... A) 5$\mu$F. B) 7.5$\mu$F. C) 30$\mu$F. D) 15$\mu$F. Show Answer Correct Answer: B) 7.5$\mu$F. 20. How do you calculate the total impedance in a series AC circuit? A) Z = R-j(XL + XC). B) Z = R + j(XC-XL). C) Z = R * (XL + XC). D) Z = R + j(XL-XC). Show Answer Correct Answer: D) Z = R + j(XL-XC). 21. The formula for inductive reactance is A) $\frac{1}{\omega L}$. B) $\omega C$. C) $\frac{1}{\omega C}$. D) $\omega L$. Show Answer Correct Answer: D) $\omega L$. 22. Which of the following is a reason why AC is used in household wiring instead of DC? A) AC is less dangerous. B) AC can be easily transformed to higher or lower voltages. C) DC is more efficient for appliances. D) DC is easier to generate. Show Answer Correct Answer: B) AC can be easily transformed to higher or lower voltages. 23. In an RLC series circuit at resonance: A) Current is minimum. B) Impedance is maximum. C) Power factor is zero. D) Current is maximum. Show Answer Correct Answer: D) Current is maximum. 24. What device converts mechanical energy into electrical energy using alternating current? A) Transformer. B) AC Generator. C) Rectifier. D) Battery. Show Answer Correct Answer: B) AC Generator. 25. In a circuit that has both capacitance and resistance, the current will lead the voltage ..... A) Because the resistance is too small to have an effect on circuit operation. B) Because the voltage across the branches is the same. C) By some angle between 0$^\circ$ and 90$^\circ$. D) With an impedance between 0 and 1. Show Answer Correct Answer: C) By some angle between 0$^\circ$ and 90$^\circ$. ← 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