Electrical Energy and Power The SPM Physics Workbook is developed under the OneSchool.net Free Books Project. The content of this book is strictly follow Malaysia SPM (Sijil Pelajaran Malaysia) syllabus. The aim of this project is to provide a complete electronic supplementary network for students to develop selflearning skills by breaking the spoonfeed rituals and to encourage them to compile educational information from the Internet.
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1) A current of 0.50A flows through a 100 Ω resistor. Find the power dissipated from the resistor?
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2) A bulb rated 240 V, 18 W is operated from a 240V power source. Find the current flowing through the bulb.
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3) 3 light bulbs of resistance 1Ω, 2Ω and 3Ω are connected in series to a power source of 240V. Find the power of the light bulb of resistance 2Ω.
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4)
The figure above shows that an ideal battery is connected in parallel to two resistors with resistances 2 Ω and 4 Ω. Find the power dissipated in the 2 Ω resistor.
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5) Find the total power dissipated in the circuit above.
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6) Find the total power dissipated in the circuit above.
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7) A 2000W heater is used to heat 500 cm^{3}of water.Find the minimum time needed to heat the water from 25 to 100 °C. (Specific Heat Capacity of water = 4200Jkg^{1}^{o}C^{1})
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8) An electric heater of power 3600W is used to heat water for 15 minutes. If the cost of 1 unit (kilowatthour) energy consumption is 24 cent, what is the cost of this heating process?
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9) An electric motor raises a mass of 20kg to a height of 5m in 10s. Given that the electric motor is connected to a power source of 80V and current 2A. Find the efficiency of the motor.


