107年 - 107 國立中山大學_碩士班招生考試_電機系(丁組)：電路學#110050

1. A Lithium Ion battery module is rated at 12V/6Ah. A module is discharged by 0.5C constant current for 0.5 hour. Determine the power supplied by the battery module. (A)144W (B)72W (C) 36W (D)18W

2. A capacitor 0.1F is charged from 50V to 100V by a constant current 1A. Determine the energy is stored in the capacitor during this process. (A)500J (B)375J (C)250J (D)125J

3.Current flowing in a resistor 10kΩ is equal to 2mA. Determine power consumption of the resistor. (A)40kW (B)40W (C)40mW (D)40นW

4.A voltage source 10 V is applied to a series RLC circuit with parameters L=4H, C=0.25F, R=10Ω. Determine power consumption. (A)200W (B)100W (C) 50W (D)0w

5.Determine reactance of a capacitor C=20nF at 100kHz. (A)0.002Ω (B)0.0125Ω (C) 500Ω (D)80Ω

6. Determine time constant of a series RC first-order circuit with parameters C-0.25F and R=40Ω. (A)10s (B)0.1s (C)10rad (D)0.1rad

7. Current 10cos(377t) A flows into a series RL circuit with parameters L=1mH and R=10Ω. Determine average power of the RL circuit. (A)1000W (B)500W (C)250W (D)0W

8. A 1052 resistive load is applied by 100cos(377t) V. Choose a false statement. (A)instantaneous power is equal to average power (B)average power is equal to apparent power (C) power factor is equal to l (D) reactive power is equal to 0

9. For an AC circuit, choose a false statement. (A)inductive current lags inductive voltage (B)capacitive current leads capacitive voltage (C) average power of an inductor is zero (D) instantaneous power of an inductor is zero

10. Determine the power factor of a ioad with impedance 10+j10Ω. (A)0.707 leading (B)0.707 lagging (C)0.866 leading (D)0.866 lagging

11. A delta-connected resistive load 100Ωper phase is connected to a balanced three-phase three-wire 200V circuit. Choose a false statement. (A)power factor is 1 (B) reactive power is0 (C)average power is 1200W (D) line current is 2A

12. A Y-connected resistive load 40Ω per phase is connected to a balanced three-phase four-wire voltage source. Phase voltage is 100V. A neutral line with resistance 10Ω is connected between source and load. Determine current in the neutral line. (A)10A (B)2A (C)2.5A (D)0A

13. For an ideal transformer, voltage at the primary side and the secondary side are 500V and 100V, respectively. Secondary side is connected to a 100Ω resistor. Choose a false statement. (A)output power is 100W (B)input power is 100W (C)output current is 1A (D) input current is 1A

14. For a two-winding coupling device in an AC circuit, choose a false statement. (A)coupling coefficient is less than 1 (B) mutual inductance is between -1 and 1 (C) induced voltage is determined by Faraday's law (D)direction of induced voltage is determined by Lenz's law

15. Determine RMS value of a half-wave rectified sine wave with amplitude 100V. (A)141.4V (B)100V (C) 70.7V (D)50V

16. An ideal buck converter is operated in CCM mode. Input voltage is 20V, output voltage is 10V and load resistance is 2Ω. Determine the average value of switch current. (A)2.5 A (B) 5 A (C)10A (D)20 A

17. An ideal boost converter is operated in CCM mode. Input voltage is 10V and output voltage is 50V and load resistance is 10Ω. Determine the average value of diode current. (A)5A (B)4A (C) 2A (D)1A

18. Determine the speed of rotation of a synchronous generator with parameters 480V/60Hz/six poles/delta-connection. (A)3600rpm (B)1800rpm (C)1200rpm (D)900rpm

19. A four-pole, 60Hz induction motor supplies 15kW to a load at a speed of 1710 rpm. Determine rotor frequency at this condition. (A)3Hz (B)6Hz (C)63Hz (D)57Hz

複選題
20. Consider load flow in an inductive feeder. Choose a true statement. (A)real power flow is primarily determined by voltage difference between two buses (B) reactive power flow is primarily determined by angle difference between two buses (C)injection of reactive power increases voltage (D)consumption of real power increases voltage

107年 - 107 國立中山大學_碩士班招生考試_電機系(丁組)：電路學#110050

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