This quiz works best with JavaScript enabled. Home > Class 12 > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 13 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 13 (25 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. Alternating current changes A) Its magnitude as well as direction. B) Only direction but not magnitude. C) Only magnitude but not direction. D) Does not change anything. Show Answer Correct Answer: A) Its magnitude as well as direction. 2. What is the effect of increasing the strength of the magnetic field on the emf generated? A) It decreases the emf. B) It only affects the frequency. C) It increases the emf. D) It has no effect. Show Answer Correct Answer: C) It increases the emf. 3. What is the difference between step-up and step-down transformers? A) Step-up transformers increase voltage; step-down transformers decrease voltage. B) Both transformers increase voltage but differ in size. C) Step-up transformers decrease voltage; step-down transformers increase voltage. D) Step-up transformers convert AC to DC; step-down transformers convert DC to AC. Show Answer Correct Answer: A) Step-up transformers increase voltage; step-down transformers decrease voltage. 4. The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an AC supply of 120V and the current flowing in it is 10A. The voltage and the current in the secondary are A) 240V, 5A. B) 240V, 10A. C) 60V, 20A. D) 120V, 20A. Show Answer Correct Answer: A) 240V, 5A. 5. What role do transformers play in reducing energy losses in AC systems? A) They convert AC to DC to reduce losses. B) They allow for high-voltage transmission, which reduces current and losses. C) They increase the frequency of AC to reduce losses. D) They store excess energy to reduce losses. Show Answer Correct Answer: B) They allow for high-voltage transmission, which reduces current and losses. 6. The behavior of resistance in pure resistor is frequency A) Dependent. B) Independent. C) No response. D) None of these. Show Answer Correct Answer: B) Independent. 7. One type of nonsinusoidal waveform is the ..... A) Square wave. B) Sine wave. C) Phase angle wave. D) Peak wave. Show Answer Correct Answer: A) Square wave. 8. What is the key feature of alternating current? A) The current only moves in one direction. B) The current constantly changes direction. C) The current is measured in Hertz. D) The current is shown on an oscilloscope. Show Answer Correct Answer: B) The current constantly changes direction. 9. In a series RLC circuit, derive the expression for the total voltage across the circuit components $V_{total}$ A) $V_{total} = I\cdot Z$. B) $V_{total} = V_{R} + V_{L} + V_{C}$. C) $V_{total} = \sqrt{V_{R}^{2} + (V_{L}-V_{C})^{2}}$. D) $V_{total} = \dfrac{P}{I}$. Show Answer Correct Answer: C) $V_{total} = \sqrt{V_{R}^{2} + (V_{L}-V_{C})^{2}}$. 10. Electrical energy is transferred through ..... in a transformer. A) Electric field. B) Rotor. C) Electromagnetic field. D) Air space. Show Answer Correct Answer: C) Electromagnetic field. 11. Which does not allow DC to pass through? A) INDUCTOR. B) RESISTOR. C) CAPACITOR. D) DIODE. Show Answer Correct Answer: C) CAPACITOR. 12. In frequency modulation, the amplitude of carrier waves is: A) Increases. B) Remains constant. C) Decreases. D) None of these. Show Answer Correct Answer: B) Remains constant. 13. If the time for one cycle is 0.1 second, the frequency is ..... A) 0.1Hz. B) 0.5Hz. C) 1Hz. D) 10Hz. Show Answer Correct Answer: D) 10Hz. 14. What happens to the induced current when there is relative motion between a conductor and magnetic field lines? A) It stops. B) It is produced. C) It becomes constant. D) It decreases. Show Answer Correct Answer: B) It is produced. 15. Those statement describe period except A) Time required for a sine wave to complete one full cycle. B) It is equal to frequency. C) Unit = second. D) T = 1/f. Show Answer Correct Answer: B) It is equal to frequency. 16. What is the effect of inductance on AC current? A) Inductance causes the AC current to lead the voltage. B) Inductance increases the effective current without changing impedance. C) Inductance has no effect on AC current. D) Inductance causes the AC current to lag behind the voltage, increasing impedance and reducing effective current. Show Answer Correct Answer: D) Inductance causes the AC current to lag behind the voltage, increasing impedance and reducing effective current. 17. High potential voltage produced by three-phase generators commonly used in A) Filament. B) X-ray tube. C) Transformer. D) Anode. Show Answer Correct Answer: B) X-ray tube. 18. What is the typical frequency of AC used in Great Britain? A) 50 Hz. B) 60 Hz. C) 100 Hz. D) 120 Hz. Show Answer Correct Answer: A) 50 Hz. 19. An ac voltage $\varepsilon = \varepsilon_{0} \sin \omega t$ $C$ $i$ A) $i = i_{m} \sin (\omega t + \pi/2)$. B) $i = i_{m} \sin (\omega t-\pi/2)$. C) $i = i_{m} \sin \omega t$. D) $i = i_{m}\cos \omega t$. Show Answer Correct Answer: A) $i = i_{m} \sin (\omega t + \pi/2)$. 20. Describe the function of a transformer in electrical circuits. A) A transformer changes voltage levels in electrical circuits. B) A transformer converts AC to DC power. C) A transformer stores electrical energy for later use. D) A transformer increases current levels in electrical circuits. Show Answer Correct Answer: A) A transformer changes voltage levels in electrical circuits. 21. At resonance frequency ..... A) Impedence is minimum, rms current flow is maximum. B) Impedence is maximum, rms current flow is minimum. C) Impedene is zero, rms current flow is maximum. D) Impedence is increasing, rms current flow is decreasing. Show Answer Correct Answer: A) Impedence is minimum, rms current flow is maximum. 22. Fill in the blank:Hair growth will be finer in ..... A) Texture. B) Length. C) Color. D) Volume. Show Answer Correct Answer: A) Texture. 23. What is a sine wave and how is it related to AC? A) A sine wave is a random fluctuation in voltage. B) A sine wave is a square wave used in digital circuits. C) A sine wave is a smooth periodic oscillation that represents the voltage and current in alternating current (AC) systems. D) A sine wave is a type of direct current (DC) signal. Show Answer Correct Answer: C) A sine wave is a smooth periodic oscillation that represents the voltage and current in alternating current (AC) systems. 24. Define reactance in the context of AC circuits. A) Reactance is the power factor of an AC circuit. B) Reactance is the measure of voltage in a circuit. C) Reactance is the opposition to AC current caused by inductance and capacitance. D) Reactance is the total resistance in a DC circuit. Show Answer Correct Answer: C) Reactance is the opposition to AC current caused by inductance and capacitance. 25. (c) How long does one cycle of this ac supply last? A) 2 s. B) 0.02 s. C) 0.2 s. D) 5 s. Show Answer Correct Answer: B) 0.02 s. ← 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