Question

Raman is a student of Class X. Raman's mother was making tea in an old electric kettle having a metal case. She switched on the power supply to the electric kettle. When LS Raman's mother touched the metal case of the working electric kettle unknowingly, she got a severe electric shock. Raman put off the main switch quickly. After removing the kettle plug from the socket, Raman found that the connecting cord was torn where it touched the metal case of the kettle. He also found that though the red and black wires of the connecting cord were firmly connected to the two lower terminals of the power plug but the green wire of the cord was not connected to the upper terminal of the plug. Raman replaced the torn connecting cord and also connected the three wires of the cord firmly to the power plug terminals.

1. Why did Raman put off the main switch quickly?
2. What name is given to the red, black and green wires of the connecting cord?
3. Which wire, red, black or green, touched the metal case of the electric kettle when Raman's mother got an electric shock?
4. Which safety device was not working in the electric kettle circuit which could have prevented the electric shock?
5. What values are displayed by Raman in this incident?

Answer 1

1. Raman put off the main switch quickly to cut off the electric supply and save his mother from the severe electric shock.
2. The names given to the wires are as follows:
   • Red wire: Live wire
   • Black wire: Neutral wire
   • Green wire: Earth wire
3. The red wire (live wire) touched the metal case of the electric kettle.
4. The earthing system (or Earth wire connection) was not working because the green wire was disconnected from the plug.
5. The values displayed by Raman are as follows:
   • Presence of mind and quick decision-making.
   • Love and care for his mother.
   • Practical application of scientific knowledge.