This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 24 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 24 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. The number of complete oscillations of the signal per unit time Is defined by? A) Period. B) Peak current. C) Frequency. D) None of the above. Show Answer Correct Answer: C) Frequency. 2. The correct expression for a.c. is A) I=I$_{o}$sin wt. B) I=I$_{o}$sin wt/2. C) I=I$_{o}$sin$^{2}$ wt. D) I=I$_{o}$sin$^{3}$ wt. Show Answer Correct Answer: A) I=I$_{o}$sin wt. 3. Rms value of ac current is the equivalent direct current which produces A) The same average energy. B) The same power dissipation. C) The same rate of current flow. D) The same rate of power use. Show Answer Correct Answer: B) The same power dissipation. 4. The transformation ratio (k = $\frac{Vs}{Vp}$ A) One. B) Greater than one. C) Less than one. D) The ratio greater or less than one depends on the other factors. Show Answer Correct Answer: B) Greater than one. 5. The core of a transformer is laminated because A) Energy losses due to eddy currents may be minimised. B) The weight of the transformer may be reduced. C) Rusting of the core may be prevented. D) Ratio of voltages in primary and secondary may be increased. Show Answer Correct Answer: A) Energy losses due to eddy currents may be minimised. 6. The repetition of a variable quantity, recurring at equal intervals, is known as ..... A) Waveform. B) Instantaneous value. C) Cycle. D) Period. Show Answer Correct Answer: C) Cycle. 7. What is the relationship between voltage and current in a purely resistive AC circuit? A) Voltage and current are in phase and directly proportional in a purely resistive AC circuit. B) Voltage leads current by 90 degrees in a purely resistive AC circuit. C) Voltage is inversely proportional to current in a purely resistive AC circuit. D) Voltage and current are out of phase in a purely resistive AC circuit. Show Answer Correct Answer: A) Voltage and current are in phase and directly proportional in a purely resistive AC circuit. 8. What factors affect the amount of emf generated? A) The color of the conductor. B) Temperature and humidity. C) Density of the magnetic flux, length of conductor, and rate of cutting lines of force. D) The type of insulation used. Show Answer Correct Answer: C) Density of the magnetic flux, length of conductor, and rate of cutting lines of force. 9. Which of the following appliances uses a motor powered by AC? A) Table lamp. B) Electric fan. C) Wireless mouse. D) Digital clock. Show Answer Correct Answer: B) Electric fan. 10. North pole induces ..... A) Clockwise current. B) Anti-clockwise current. C) Zero current. D) Infinite current. Show Answer Correct Answer: B) Anti-clockwise current. 11. Besarnya daya pada rangkaian arusbolak-balik antara teori dengan hasilsesungguhnya dari hasil pembacaan alatukur tidak sama, hal ini disebabkanadanya A) Adanya hambatan semu yang berasal dariinduktor (XL) dan kapasitor (XC). B) Adanya hambatan seri yang berasal dariinduktor (XL) dan kapasitor (XC). C) Adanya hambatan searah yang berasal dariinduktor (XL) dan kapasitor (XC). D) Adanya hambatan berlawanan yang berasal dariinduktor (XL) dan kapasitor (XC). Show Answer Correct Answer: A) Adanya hambatan semu yang berasal dariinduktor (XL) dan kapasitor (XC). 12. What is the main difference between AC and DC? A) AC flows in one direction, DC alternates direction. B) AC alternates direction, DC flows in one direction. C) Both AC and DC alternate direction. D) Both AC and DC flow in one direction. Show Answer Correct Answer: B) AC alternates direction, DC flows in one direction. 13. The highest value reached by the voltage or current in one cycle is called: A) Instantaneous value. B) Peak to peak value. C) Peak value. D) Root mean square value. Show Answer Correct Answer: C) Peak value. 14. What is the main reason for not using direct current (d.c.) for transmission and distribution? A) Transformers do not work with d.c. B) D.c. is more expensive. C) D.c. is less efficient. D) D.c. is less reliable. Show Answer Correct Answer: A) Transformers do not work with d.c. 15. What is the role of capacitive reactance in an AC circuit? A) Capacitive reactance opposes changes in voltage and allows current to flow freely. B) Capacitive reactance increases the overall resistance in the circuit. C) Capacitive reactance causes the current to lead the voltage, affecting the overall circuit behavior. D) Capacitive reactance has no effect on the current in an AC circuit. Show Answer Correct Answer: C) Capacitive reactance causes the current to lead the voltage, affecting the overall circuit behavior. 16. $V_{rms}$ A) 275 W. B) 366 W. C) 550 W. D) 1100 Wi. Show Answer Correct Answer: A) 275 W. 17. How does AC allow for easy voltage transformation? A) By using transformers to step up or step down the voltage. B) By changing the frequency of the current. C) By using capacitors to store energy. D) By converting to DC first. Show Answer Correct Answer: A) By using transformers to step up or step down the voltage. 18. What is the impact of phase difference on the operation of transformers? A) Phase difference impacts voltage/current relationship and efficiency in transformers. B) Phase difference only affects physical size of transformers. C) Phase difference has no effect on transformer operation. D) Phase difference only influences the color of transformer insulation. Show Answer Correct Answer: A) Phase difference impacts voltage/current relationship and efficiency in transformers. 19. If a transformer has 200 turns in the primary, 100 turns in the secondary, and 150VAC applied to the primary, the voltage across the secondary is ..... A) 75VAC. B) 90VAC. C) 120VAC. D) 140VAC. Show Answer Correct Answer: A) 75VAC. 20. The effective voltage value is A) 25%. B) 50%. C) 71%. D) 90%. Show Answer Correct Answer: C) 71%. 21. The resistor in an AC will cause A) No phase difference. B) V lead I. C) I lead V. D) I lags V. Show Answer Correct Answer: A) No phase difference. 22. Defines of the effective value of alternating current 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: C) Steady current which delivers the same average power as the a.c. to a resistive load. 23. Which term describes the maximum value of current or voltage in an AC cycle? A) RMS Value. B) Peak Value. C) Average Value. D) Instantaneous Value. Show Answer Correct Answer: B) Peak Value. 24. An inductor, a resistor and a capacitor are joined in series with an ac source. As the frequency of the source is slightly increased from a very low value, the reactance of the A) Inductor increases. B) Resistor increases. C) Capacitor increases. D) None of the above. Show Answer Correct Answer: A) Inductor increases. 25. The transformation ratio in the step up transformer is A) One. B) Greater than one. C) Less than one. D) The ratio greater or less than one depends on the other factor. Show Answer Correct Answer: B) Greater than one. ← 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