Greenridge Sec Physics 2024 Chapter 19 Notes

Secondary Four Express Chapter 19 – Practical Electricity Physics Notes - 1 - Prepared by: Mr. Yong W. S. Greenridge Secondary School Secondary Four Express Physics Chapter 19 – Practical Eectricity Name: ( ) Class: 4-9 Date: 2 May 2024 At the end of this chapter, you should be able to ☺ Describe the use of the heating effect of electricity in appliances such as electric kettles, ovens and heaters. ☺ Recall the relationship P = VI and E = VIt. ☺ Apply the relationships for electrical power and energy to new situations or to solve related problems. ☺ Calculate the cost of using electrical appliances where the energy unit is kWh. ☺ State the hazards of using electricity in the following situations: (i) damaged insulation (ii) overheating of cables (iii) damp conditions. ☺ Compare the use of non-renewable and renewable energy sources such as fossil fuels, nuclear energy, solar energy, wind energy and hydroelectric generation to generate electricity in terms of energy conversion efficiency, cost per kWh produced and environmental impact. ☺ Explain the use of fuses and circuit breakers in electrical circuits and of fuse ratings. ☺ Explain the need for earthing metal cases and for double insulation. ☺ State the meaning of the terms, live, neutral, and earth. ☺ Describe how to wire a mains plug. ☺ Explain why switches, fuses and circuit breaker are wired into the live-conductor. 19.1 Measurement of Electrical Energy Electrical Power, P Name Unit Formula 50 W means.. Electrical Power

Secondary Four Express Chapter 19 – Practical Electricity Physics Notes - 2 - Prepared by: Mr. Yong W. S. Example 1 A bulb uses a 3 V supply and takes a current of 0.2 A. What is the power rating of the bulb? Electric Energy, E Name Unit Formula Electrical Energy Example 2 A filament lamp is rated 60 W and 240 V. Find (a) the current flowing through the lamp. (b) the resistance of the filament and (c) the energy produced by the lamp in one hour. Example 3 An electric iron has a heating element of resistance 80 . If the operating current flowing through is 4 A, calculate (a) the supply voltage. (b) the electrical power produced and (c) the heat energy produced in 5 minutes,

Secondary Four Express Chapter 19 – Practical Electricity Physics Notes - 3 - Prepared by: Mr. Yong W. S. Calculating the cost of electricity consumption  Electrical energy consumed in household appliances is measured in ( ).  1 kWh is the .  To calculate energy in kWh: Example 4 If Singapore Power charges 15 cents for each kWh of electrical energy used, calculate the total cost of using a 5 kW electric kettle for 15 minutes and a 200 W filament bulb for 2 hours. 19.2 Some Uses of Electricity (Refer to textbook) Electric Heating Electric Lighting