This quiz works best with JavaScript enabled. Home > Cbse > Class 12 > Science > Physics Part I > Class 12 Physics (Part I) Chapter 7 Alternating Current – Quiz 10 🏠 Homepage 📘 Download PDF Books 📕 Premium PDF Books Class 12 Physics (Part I) Chapter 7 Alternating Current Quiz 10 (60 MCQs) Quiz Instructions Select an option to see the correct answer instantly. 1. Which of the following can act as an inductor? I. A long coil II. A long wireIII. A conducting sphere A) I. B) III. C) I and II. D) II and III. E) All of the above. Show Answer Correct Answer: A) I. 2. The phase difference between instantaneous voltage and current of purely capacitive circuit is A) 180. B) 90. C) 360. D) 0. Show Answer Correct Answer: B) 90. 3. A alternating current of peak value I$_{o}$ passes through a heater of resistance R.What is the mean power output of the heater? A) $2I_o^2R$. B) $\frac{I_o^2R}{\sqrt{2}}$. C) $I_o^2R\sqrt{2}$. D) $I_o^2R$. E) $\frac{I_o^2R}{2}$. Show Answer Correct Answer: E) $\frac{I_o^2R}{2}$. 4. The sum of resistance and reactance is referred to as ..... A) Geometric resistance. B) Susceptance. C) Conductance. D) Impedance. Show Answer Correct Answer: D) Impedance. 5. A bicycle generator creates 3 V, when bicycle is travelling with a speed of 9.0 km/h, the emf generated. The emf will be, when travelling with 15 km/h A) 20 V. B) 5.0 V. C) 10 V. D) 0 V. Show Answer Correct Answer: B) 5.0 V. 6. What is the destructive force of alternating current in beauty therapy? A) It creates thermal heat by friction, agitating molecules and causing them to vibrate. B) It cools the skin tissues. C) It increases blood flow. D) It reduces tissue swelling. Show Answer Correct Answer: A) It creates thermal heat by friction, agitating molecules and causing them to vibrate. 7. A power factor is not an angular measure, but a numerical ratio with a value between 0 and 1, equal to the ..... A) Cosine of the phase angle. B) Sine of the phase angle. C) Tangent of the phase angle. D) Cotangent of the phase angle. Show Answer Correct Answer: A) Cosine of the phase angle. 8. In LCR circuit, the capacitance is changed from C to 4C. For the same resonant frequency, the inductance should be changed from L to ..... A) L / 2. B) 4L. C) 2L. D) L / 4. Show Answer Correct Answer: D) L / 4. 9. Which of the following electrical devices is NOT used for controlling current and voltage in an alternating current (AC) circuit? A) Transistor. B) Capacitor. C) Resistor. D) Inductor. Show Answer Correct Answer: A) Transistor. 10. Coagulation converts liquid into solid through heating the tissues, breaking down the proteins within the molecules of the tissues to congeal or set. A) True. B) False. C) All the above. D) None of the above. Show Answer Correct Answer: A) True. 11. An A.C source is connected to a resistive circuit. Which of the following is true? A) Current leads the voltage and both are in same phase. B) Current lags behind the voltage and both are in same phase. C) Current and voltage are in same phase. D) Any of the above may be true depending upon the value of resistance. Show Answer Correct Answer: C) Current and voltage are in same phase. 12. Power Consumed by an Inductor in a half cycle is A) Zero. B) Irms x Vrms. C) Irms x Vrms / 2. D) Imax x Vmax /2. Show Answer Correct Answer: B) Irms x Vrms. 13. If a household appliance is rated at 220V AC, what does this mean? A) It operates only on DC voltage. B) It uses 220 volts of direct current. C) It requires 220 volts of alternating current to function. D) It can operate at any voltage. Show Answer Correct Answer: C) It requires 220 volts of alternating current to function. 14. Which of the following is a characteristic of a single-phase AC system? A) It has a constant power output. B) It is more efficient for large motors. C) It is typically used in residential homes. D) It requires three conductors. Show Answer Correct Answer: C) It is typically used in residential homes. 15. What is the peak voltage in an AC circuit? A) The peak voltage is the maximum voltage in an AC circuit. B) The peak voltage is the average voltage in an AC circuit. C) The peak voltage is the minimum voltage in an AC circuit. D) The peak voltage is the voltage at the midpoint of the AC waveform. Show Answer Correct Answer: A) The peak voltage is the maximum voltage in an AC circuit. 16. AC power is transmitted from a power house at high voltage as A) The rate of transmission is faster at high voltages. B) A precaution against theft of transmission lines. C) Power cannot be transmitted at low voltages. D) It is more economical due to less power loss. Show Answer Correct Answer: D) It is more economical due to less power loss. 17. An ac voltage $V = V_{m} \sin \omega t$ $C$ A) $i = I_{m} \sin \omega t$. B) $i = I_{m} \sin (\omega t + \pi/2)$. C) $i = I_{m}\cos \omega t$. D) $i = I_{m} \sin (\omega t-\pi/2)$. Show Answer Correct Answer: B) $i = I_{m} \sin (\omega t + \pi/2)$. 18. What does the acronym ELI stand for A) Energy Last Internal. B) Voltage Lags Current in Inductor Circuits. C) Voltage Leads Current in Capacitor Circuits. D) Voltage Leads Current in Inductor Circuits. Show Answer Correct Answer: D) Voltage Leads Current in Inductor Circuits. 19. Root mean square of ac current is the A) Value of dc that dissipates same power as ac through a resistor. B) Instantaneous value of current. C) Value of dc that dissipates same heat as ac through a resistor. D) Average current. Show Answer Correct Answer: A) Value of dc that dissipates same power as ac through a resistor. 20. What is the purpose of a transformer in an AC circuit? A) To change the voltage level of AC current. B) To increase the frequency of AC current. C) To store electrical energy in a circuit. D) To convert AC to DC current. Show Answer Correct Answer: A) To change the voltage level of AC current. 21. A transformer steps up 220 V to2200 V. What is the transformation ratio? A) 20. B) 0.1. C) 10. D) 0.2. Show Answer Correct Answer: C) 10. 22. Transformation ratio of a step-up transformer is A) Greater than one. B) Less than one. C) Equal to one. D) None of these. Show Answer Correct Answer: A) Greater than one. 23. The primary of a step-down transformer used for ringing door bell has 2000 turns of fine wire and the secondary has 100 turns .The transformer when connected at a potential difference of A) 55 V. B) 11V. C) 5.5 V. D) 220V. Show Answer Correct Answer: B) 11V. 24. 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. 25. The correct expression for a.c. is A) I=I$_{o}$sin wt. B) I=I$_{o}$sin$^{3}$ wt. C) I=I$_{o}$sin$^{2}$ wt. D) I=I$_{o}$sin wt/2. Show Answer Correct Answer: A) I=I$_{o}$sin wt. 26. Rms value of ac current is the equivalent direct current which produces A) The same power dissipation. B) The same average energy. C) The same rate of power use. D) The same rate of current flow. Show Answer Correct Answer: A) The same power dissipation. 27. The transformation ratio (k = $\frac{Vs}{Vp}$ A) Less than one. B) One. C) Greater than one. D) The ratio greater or less than one depends on the other factors. Show Answer Correct Answer: C) Greater than one. 28. 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. 29. The repetition of a variable quantity, recurring at equal intervals, is known as ..... A) Instantaneous value. B) Period. C) Cycle. D) Waveform. Show Answer Correct Answer: C) Cycle. 30. 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. 31. 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. 32. Which of the following appliances uses a motor powered by AC? A) Wireless mouse. B) Electric fan. C) Digital clock. D) Table lamp. Show Answer Correct Answer: B) Electric fan. 33. North pole induces ..... A) Clockwise current. B) Zero current. C) Anti-clockwise current. D) Infinite current. Show Answer Correct Answer: C) Anti-clockwise current. 34. 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 searah yang berasal dariinduktor (XL) dan kapasitor (XC). C) Adanya hambatan berlawanan yang berasal dariinduktor (XL) dan kapasitor (XC). D) Adanya hambatan seri yang berasal dariinduktor (XL) dan kapasitor (XC). Show Answer Correct Answer: A) Adanya hambatan semu yang berasal dariinduktor (XL) dan kapasitor (XC). 35. The highest value reached by the voltage or current in one cycle is called: A) Peak to peak value. B) Root mean square value. C) Peak value. D) Instantaneous value. Show Answer Correct Answer: C) Peak value. 36. What is the main reason for not using direct current (d.c.) for transmission and distribution? A) D.c. is less reliable. B) D.c. is less efficient. C) Transformers do not work with d.c. D) D.c. is more expensive. Show Answer Correct Answer: C) Transformers do not work with d.c. 37. 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. 38. How does AC allow for easy voltage transformation? A) By using capacitors to store energy. B) By converting to DC first. C) By using transformers to step up or step down the voltage. D) By changing the frequency of the current. Show Answer Correct Answer: C) By using transformers to step up or step down the voltage. 39. 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. 40. 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) 140VAC. B) 90VAC. C) 75VAC. D) 120VAC. Show Answer Correct Answer: C) 75VAC. 41. The effective voltage value is A) 90%. B) 50%. C) 71%. D) 25%. Show Answer Correct Answer: C) 71%. 42. The resistor in an AC will cause A) V lead I. B) I lead V. C) I lags V. D) No phase difference. Show Answer Correct Answer: D) No phase difference. 43. 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. 44. Which term describes the maximum value of current or voltage in an AC cycle? A) RMS Value. B) Average Value. C) Peak Value. D) Instantaneous Value. Show Answer Correct Answer: C) Peak Value. 45. 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. 46. What is the current flow in a purely resistive AC circuit if the resistance is 15 ohms and the voltage is 150V? A) 18A. B) 22A. C) 14A. D) 10A. Show Answer Correct Answer: D) 10A. 47. Which quantity decides heating effect in AC? A) RMS current. B) Average current. C) Peak current. D) Instantaneous current. Show Answer Correct Answer: A) RMS current. 48. Lenz' law is in accordance with the law of conservation of A) Energy. B) Mass. C) Momentum. D) Charge. Show Answer Correct Answer: A) Energy. 49. Why is AC preferred over DC for transmitting electricity over long distances? A) DC is safer. B) AC can be easily transformed to different voltages. C) DC is more efficient. D) AC is more expensive. Show Answer Correct Answer: B) AC can be easily transformed to different voltages. 50. The use of inductor? A) Passive component that limit the current flow. B) Passive component that store electric charge in an AC circuit. C) Passive component that store energy in a magnetic field when electric current flow through it. D) Passive component that store food in a fridge when electric current flows through it. Show Answer Correct Answer: C) Passive component that store energy in a magnetic field when electric current flow through it. 51. Fill in the blank:Hair growth will be lighter in ..... A) Volume. B) Colour. C) Length. D) Texture. Show Answer Correct Answer: B) Colour. 52. A light bulb of resistance $484\, \Omega$ $220\, \text{V}$ A) $0.45\, \text{A}$. B) $0.31\, \text{A}$. C) $0.64\, \text{A}$. D) $1.28\, \text{A}$. Show Answer Correct Answer: C) $0.64\, \text{A}$. 53. A pure inductor is connected to an AC power supply. In this circuit, the current A) Leads the voltage by 90$^\circ$. B) Lags the voltage by 90$^\circ$. C) Is in phase with the voltage. D) None of the given answers. Show Answer Correct Answer: B) Lags the voltage by 90$^\circ$. 54. What is the step-down turns ratio of a transformer with 200 turns in the primary and 100 turns in the secondary? A) 3:4. B) 1:2. C) 2:2. D) 2:1. Show Answer Correct Answer: D) 2:1. 55. In an ideal inductor, what is the power consumed? A) Zero. B) Variable. C) Maximum. D) Minimum. Show Answer Correct Answer: A) Zero. 56. At resonance, circuit behaves like: A) Inductor. B) Pure resistor. C) Open circuit. D) Capacitor. Show Answer Correct Answer: B) Pure resistor. 57. A 230V, 50Hz voltage is applied to a coil having L = 5H and R = 2 Ohm in series with capacitance C. When the voltage across the coil is 400V, find the current in the circuit? A) 0.4583 A. B) 0.1578 A. C) 0.1465 A. D) 0.2547 A. Show Answer Correct Answer: D) 0.2547 A. 58. In an AC circuit, what is the effect of a resistor? A) Opposes the flow of current. B) Generates magnetic fields. C) Stores electrical energy. D) Increases voltage. Show Answer Correct Answer: A) Opposes the flow of current. 59. Which of the following is a correct safety procedure when unplugging an AC appliance? A) Pull the cord sharply. B) Hold the plug firmly and pull it out. C) Use wet hands. D) Touch the metal prongs. Show Answer Correct Answer: B) Hold the plug firmly and pull it out. 60. Alternating current is represented by A) Sine wave. B) Triangular wave. C) Square wave. D) All of the above. Show Answer Correct Answer: D) All of the above. ← PreviousNext →Related QuizzesScience QuizzesClass 12 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 8 🏠 Back to Homepage 📘 Download PDF Books 📕 Premium PDF Books