Mains Electricity
Visão Geral
Every time you plug in a kettle, charge a phone, or switch on a lamp, you rely on a system designed to deliver energy safely. The UK mains supply provides 230 V of alternating current at 50 Hz, and understanding how that power reaches your appliance, how the wiring inside a plug is arranged, and what protects you from a fault is essential knowledge for both your exam and everyday life.
This topic takes you inside the three-pin plug, explains why fuses and circuit breakers exist, shows you how to calculate electrical power and energy transferred, and clarifies the difference between alternating and direct current. You will practise selecting the right fuse for an appliance and solving energy-transfer problems using the equations examiners expect.
Objetivos
- Understand how the use of insulation, double insulation, earthing, fuses and circuit breakers protects the device or user in a range of domestic appliances
- Understand why a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts
- Know and use the relationship between power, current and voltage: power = current x voltage, P = I x V, and apply the relationship to the selection of appropriate fuses
- Use the relationship between energy transferred, current, voltage and time: energy transferred = current x voltage x time, E = I x V x t
- Know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery
Mapa mental
Este tema esta mapeado para mostrar como as ideias se ligam.
Abra o mapa mental na aplicacao
Cartoes
Pratica rapida de memoria sobre o que e avaliado neste tema.
Pratique estes cartoes na aplicacao
Nota de Aula
Apontamento completo disponivel na aplicacao Green Bridge
Instale a aplicacao Green Bridge CBT no telemovel ou computador para aceder a biblioteca IGCSE completa: exames anteriores, criterios de correcao, mapas mentais, cartoes de estudo e licoes em audio.
Avaliação da Lição
Parabéns por concluir a lição em Mains Electricity. Agora que você explorou o conceitos e ideias-chave, é hora de colocar seu conhecimento à prova. Esta seção oferece uma variedade de práticas perguntas destinadas a reforçar sua compreensão e ajudá-lo a avaliar sua compreensão do material.
Irá encontrar uma mistura de tipos de perguntas, incluindo perguntas de escolha múltipla, perguntas de resposta curta e perguntas de redação. Cada pergunta é cuidadosamente elaborada para avaliar diferentes aspetos do seu conhecimento e competências de pensamento crítico.
Use esta secção de avaliação como uma oportunidade para reforçar a tua compreensão do tema e identificar quaisquer áreas onde possas precisar de estudo adicional. Não te deixes desencorajar pelos desafios que encontrares; em vez disso, vê-os como oportunidades de crescimento e melhoria.
- What colour is the live wire in a UK three-pin plug? A) Blue B) Green and yellow C) Brown D) Red Answer: C
- The UK mains electricity supply has a frequency of: A) 50 V B) 230 Hz C) 50 Hz D) 230 V Answer: C
- A 460 W appliance is connected to the 230 V mains supply. What fuse should be used? A) 1 A B) 3 A C) 5 A D) 13 A Answer: B
- Which safety device can be reset after it trips? A) Fuse B) Earth wire C) Circuit breaker D) Double insulation Answer: C
- An appliance that is double insulated does not need: A) A live wire B) A neutral wire C) A fuse D) An earth wire Answer: D
Resolva estas questoes na aplicacao
Resolva estas questoes na aplicacao
Livros Recomendados
Para aprender mais, fontes abertas
-
Secção do manual
Electrical Safety: Systems and Devices
Electricity has two hazards. A thermal hazard occurs when there is electrical overheating. A shock hazard occurs when electric current passes through a person. Both hazards have already been discussed. Here we will concentrate on systems and devices that prevent electrical hazards. Figure 23.31 show
"College Physics: Electrical Safety: Systems and Devices" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/23-8-electrical-safety-systems-and-devices. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
-
Secção do manual
Electric Power and Energy
Power is associated by many people with electricity. Knowing that power is the rate of energy use or energy conversion, what is the expression for electric power ? Power transmission lines might come to mind. We also think of lightbulbs in terms of their power ratings in watts. Let us compare a 25-W
"College Physics: Electric Power and Energy" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/20-4-electric-power-and-energy. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Publicados por outras organizações com licenças abertas e creditados como pedem. As ligações abrem os seus sites.
Pratique Questões Simuladas
Quer praticar questões simuladas sobre Mains Electricity? Descarregue a aplicação Green Bridge CBT para aceder a questões simuladas e avaliações completas sobre este tópico.
Descarregar a aplicação na Google Play Store
Tudo o que precisas para te destacares no JAMB, WAEC e NECO.
