Electrical power and safetyIB MYP Sciences: Flashcards

What these 14 flashcards ask

State the equation for electrical power.
What is the unit of power?
State the equation for energy transferred in terms of power and time.
In what units are E, P and t when E is in joules?
What is a kilowatt-hour?
How do you work out the cost of electricity?
What colour is the live wire?
What colour is the neutral wire?
What colour is the earth wire?
What does a fuse do?
How does a circuit breaker differ from a fuse?
Why does the earth wire make a metal case safe?
What is double insulation?
What moves when you charge an insulator by rubbing?

Exam questions on Electrical power and safety

A family in Dubai uses an electric kettle rated at 2.0 kW. The kettle works from the 230 V mains supply.
Calculate the energy transferred by the kettle in 3.0 minutes, in kilowatt-hours.2 marks
A household in Auckland pays 30 cents for each kilowatt-hour (kWh) of electricity. A 1.5 kW electric heater runs for 4.0 hours each evening.
Calculate the cost of running the heater for one evening.2 marks
A washing machine in a home in Cairo is connected to the mains supply by a three-pin plug that contains a fuse. The machine has a metal case and is rated at 2300 W on the 230 V mains.
Explain how the earth wire and the fuse together protect a user if a fault makes the live wire touch the metal case.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).