Practical Electricity

Questions Worth Pondering

  1. In 3 pins plug, the pin for Earth is the longest. Why is it designed in that fashion?
  2. Voltage in neutral wire is zero. Does that mean the current in neutral wire is zero as well?
  3. What does the fuse protect? The appliance? The user?

Commonly Seen Questions

  1.  Explain what is meant by an electric kettle having a rating of 1500 W, 250V.
    • It means that when a voltage of 250v is applied, 1500 J of electrical energy is converted to thermal energy per second.
  2. Describe what happened during Earthing.
    • When there is a fault and the user touches the metal casing, the Earth wire provides a path of low resistance for the current to flow instead of the person touching the metal casing. When the current flows through the Earth wirethe surge in current causes the fuse to blow, breaking the circuit which will cut off the power supply to the appliance.

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