Introduction to Electrical Circuit 44 2.6.4 Figure 2.27: Multimeter with DC mA and AC A Range Selector Figure 2.28 shows how to measure DC current using a multimeter. Figure 2.28: Measuring DC Current Wattmeter Wattmeter is an instrument used to measure electrical power flows in a circuit. It measures the electrical power in watt. Figure 2.29 shows the symbol of wattmeter. Figure 2.29: Wattmeter Symbol Figure 2.30 shows the wattmeter used to measure the electrical power. This type of wattmeter can measure up to 1000 watt or 1kW. W
Introduction to Electrical Circuit 45 2.6.5 Figure 2.30: Wattmeter Kilowatt-Hour (kWh) Meter Energy meter or kilowatt-hour (kWh) meter is used to measure total electrical energy consumes by the electrical load. The electrical energy measure is in kilowatt-hour (kWh). This meter works on the principle of conversion from electrical energy into mechanical energy. Figure 2.31 below shows the symbol for the kilowatt-hour (kWh) meter. Figure 2.31: kWh Symbol Figure 2.32 shows the kWh-meter used to measure the electrical energy. Figure 2.32: kWh Meter kWh
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Answer 46 Answer Problem 1-1 Answer Problem 2-3 Question 1 a) 4.5x104 Question 1 R=666.67Ω b) 4.82x10-4 Question 2 R=10Ω c) 3.25x108 Question 3 R=10kΩ ; 2.5mA Question 2 a) 56M Question 4 a) R=60Ω b) 0.24m @ 240µ b) 960W c) 40p Question 5 a) I=0.25A Question 3 0.47µF b) R=960Ω Question 4 5µA Question 6 E=270kJ Question 5 0.056MΩ Question 7 P=315W ; E=4725J Question 6 50kV Question 8 E=7.2kJ Question 7 (d) Mass Question 9 a) P=10kW Question 8 (b) 2200 b) I=40A Question 9 (a) C c) E=10kWh Question 10 (c) Frequency Question 10 a) E=4.8MJ b) E=1.33kWh Answer Problem 2-1 Question 1 20kΩ Answer Problem 2-4 Question 2 a) Green, Black & Yellow Question 1 RT=6Ω b) Red, Violet, Green & Gold Question 2 RT=1.62kΩ c) Orange, Orange, Black & Question 3 R3=15Ω ; P=2W Silver Question 4 V1=1.125V d) Brown, Black, Green & Gold V2=2.25V e) Orange, Red, Brown, Brown & V3=5.625V Silver Question 5 Vs=9.9V Question 3 a) 27kΩ 5% R1=99Ω b) 520Ω 1% R3=495Ω c) 45Ω Question 6 R1=7.5Ω d) 2.2kΩ 1% R2=15Ω e) 1kΩ 1 0% R3=7.5Ω Question 7 a) VT=60V b) VR1=60V Answer Problem 2-2 c) R1=30kΩ ; R2=5kΩ Question 1 R=9Ω R3=15kΩ ; RT=33.75kΩ Question 2 R=0.18Ω Question 8 a) RT=5kΩ b) IT=10mA Question 3 =1.7x10-8 c) IR2 = IR3 = 5mA Question 4 d=1.6mm Question 9 P=5.14W Question 5 l=125m Question 10 VR4=19.07V ; P=9W Question 6 R=8.75Ω ; l=5m Question 7 R=51.93Ω Question 8 R1=0.017Ω ; R2=0.026Ω Question 9 R=0.318Ω Question 10 l=3.5m Answer: