Back to the full dot-point answer
SingaporePhysicsQuick questions
Electricity and D.C. Circuits
Quick questions on Electrical energy, power and safety explained: O-Level Physics
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is electrical power?Show answer
The power of an electrical device is the rate at which it transfers energy. For a device at voltage carrying current :
What are mains safety devices?Show answer
A mains circuit has three wires: live (at high voltage), neutral (near zero), and earth (a safety connection to the ground). Safety relies on several features:
What is choosing a fuse?Show answer
A fuse should be rated just above the normal working current of the appliance. Too high and it will not blow in a fault; too low and it will blow during normal use.
What is q1?Show answer
A device runs at and draws . Calculate its power. [2 marks]
What is q2?Show answer
State the purpose of a fuse in a mains plug. [2 marks]
What is q3?Show answer
Explain why the earth wire makes an appliance with a metal case safer. [2 marks]
Have a question we have not covered?
This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.