2/B 67% + 16 A D.C. circuit has been setup as shown in Figure 1(a). Apply the Kirchhoff's Voltage Low to resolve questio

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2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 1 (56.26 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 2 (56.26 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 3 (62.55 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 4 (64.51 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 5 (62.04 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 6 (60.76 KiB) Viewed 28 times

2 B 67 16 A D C Circuit Has Been Setup As Shown In Figure 1 A Apply The Kirchhoff S Voltage Low To Resolve Questio 7 (68.96 KiB) Viewed 28 times

2/B 67% + 16 A D.C. circuit has been setup as shown in Figure 1(a). Apply the Kirchhoff's Voltage Low to resolve questions below. (0) Copy the below circuit to your answer book, insert the voltage arrows for (5 marks) each circuit component, and label loops in your circuit. (ii) Write the two loop equations for WXUP, and XYZU in terms of hand is. (2 marks) (iii) Determine the values of land Is. (4 marks) (iv) Calculate the power dissipation for the 32 resistor (1 mark) (v) An analogue ammeter is connected in series with the resistor Rs for (7 marks) measuring the current b. However, measured value is not matched with the calculation results. Explain the situation and propose another method to obtain a more accurate result w 11 XI: Y RI WW 10002 E 384V (1-12) ΕΙ 256V R3 3202 RS 12402 w R2 w 2802 E- 160V R4 WW U 26002 Figuren P 2 (b) A resistor network is built as shown in Figure (b). With the application of (6 marks) Kirchhoff's Current Law, determine the unknown currents lib. I, and L NI 2A WW WW M SA HAN NA 1.5A NS JA w N w USA WW N
62001).pdf 3 / 8 67% 2(a) An alloy wire with 4.0 mm diameter has resistance of 50 at a temperature of 20. Determine: 0 the length of the alloy wire, given that the resistivity of the alloy material is 3.14 x 10 m; (2 marks) (ii) the wire resistance at 40°C if the temperature coefficient of the alloy material at 20°C is 0.07 "C! (2 marks) (1 mark) (b) A production machine operates for 8 hours per day. The machine with power rating of 1200W worked for 25 days in last month and the supply voltage to the machine is 250V. If the electricity charge is HKSI 25 per kWh, please response to the following questions: (i) Determine the supply current for the production machine, and () Calculate the electricity bill for last month (11) As the industrial plant operations are costly especially for the electricity use proposed 4 methods that help reducing the energy cost for typical plants in Hong Kong environment (e) For the circuit shown in Figure 2e), determine: (2 marks) (8 marks) (1) the total resistance, R. marks) (ii) the supply current, I (2 marks) (b) the branch current. Isund (marks) (iv) the potential difference Vacross the resistor 2 marks) ly RS W 20062 40V RI HOS R WW R 55002 R R w 45002 1602 ER May 20 PARA
4 / 8 67% * 3. (a) An AC current is represented mathematically in the following form (0)-40 sin(3777- (1:6)] mA Determine the following quantities for i(1) (1) the peak current (ii) the effective (or RMS) current (ii) the frequency in Hx (iv) the phase in degree (state the phase is leading or legging) (1 mark) (2 marks) (2 marks) (2 marks) (b) A capacitance has a reactance (X.) of 500 a. It is supplied by a sinusoidal source with an angular velocity (0) of 377radis 6) Find the value of the capacitance (ii) Draw the phasor diagram of the capacitance voltage Ve and current le (Remark: Use le as reference) (2 marks) (2 marks) (c) A 220 V 50 Hza.c. circuit is connected with the loads as shown in Figure el Given that R, 50, R40 , X.-20, and Xe 50 220 V, 50 Hz 1 1 R M R X W Flus) 13 카 (d) 6) Determine the total impedance of the circuit in polar form. (2 marks (H) Determine the supply current of the circuit (b) in polar form. (2 marks) (ii) Calculate the value in polar form mark Briefly explain the reasons for using phasor method in the calculations (6 marks) of electrical quantities in AC circuits (i) State one of the limitation in using the please method for calculating (2 marks) A quantities in clectric circuits
5 / 8 67% 4. (a) A resistor network is shown in Figure 4). By applying the Kirchhoff's (6 murks) current law, determine the value of the currents , Ig and Le 1 W 15 Is-SOA w 17-100A WW 13-30A w 16-20A Figure 40 (b) As shown in Figure 4(b) a series RLC eruit is connected to a 50 V 50 Hz AC supply. The circuit consists of a 20 resistor, a 25 mH inductor, and a 200 a capacitor. 6) Determine the total impedance (2) in rectangular form (3 marks) (i) Calculate the supply current (I) in polar form, and (2 marks) thii) Calculate the voltages across the resistor (V), inductor (V), and capacitor (marks) (Vain polar form (iv) Sketch a phasor diagram to show the supply current (I). supply voltage (V). 15 marks) and voltages across the resistor (Ve). Inductor ( Vand capacitor (Ve) 50 V, 50 Hz R M. Fich (c) A student is doing is test for the LRC circuit similar with connection shown (6 marks) in Figure 4b). He takes a resistor with a low resistance value. Then, he randomly pocks an inductor and capacitor. At last, he connects a 220 V to all of them in series. However, it is found that the protection fuse of the circuit is blown. Identify the possible problem with explanation
/8 67% + PTD en Services (MS) May 2012 Papo 5. (a) A circuit consists of a capacitor an inductor L. with two resistors Rand R as shown in Figure 5(a). Determine: L-0.2H Ir M R1600 Tra 5A 30° Vs SOH C+504F R = 300 Fiesta (i) the active power Ps for resistor R$ (2 marks) (3 marks) (i) the reactive power Qc for capacitor C () the active power Ps for resistor Ri: the reactive power for inductor (3 marks) (2 marks) (the total active power Prand total reactive power or (2 marks) (1) the total apparent power Sri (2 marks) vii) the power factor of the cinci and (3 marks) viinithe source voltage Vs (2 marks) bi You are working in a factory as an engineer. To improve the overall power to marks) factor capacity banke installed for the system. However, the circuit connected with the capacity bank was tripped very often. Identity THREE possible problems with explanation that will affect the operation of the factory
6. (a) (4 marks) © State the assumptions made for an ideal iron-core transformer. Briefly explain why electricity is transmitted in very high voltage from the generating plant to the load centres (4 maris) (5) Figure 6(b) shows an ideal transformer working at full load capacity. The tum ratio of the transformer is 41. Given that the supply voltage is 220 V n.c. and the load impedance value of Z is 10+j6 22. Assume the transformer is ideal Ір Ep N Figure Determine the output voltage across the load Z 13 marks) Determine the primary current L, and the secondary current I, of the (6 marks) transformer in polar form. (l) Find out the impedance of the load referred to the primary side in polar (3 marks) form (y) If there is a high frequency noises happened on the secondary side, will (2 marks) it affect the circuit in the primary side? Give your answer with explanation (V) Sugest THREE applications of a single-phase voltage transformer 3 marks) - End of Questions