Question 9 — Suppose the '+' and '-' symbols - Questions at the end of the chapter - Chapter 3 Class 7 - Electricity: Circuits and their Components

Last updated at August 17, 2026 by

Q9 (Medium): Suppose the '+' and '-' symbols cannot be read on a battery. Suggest a method to identify the two terminals of this battery.

Answer:
We have studied that LED glows only when positive terminal connects to longer wire . This is why we can use LED to test battery terminals.

  • Connect LED longer wire to one battery terminal
  • Connect LED shorter wire to other battery terminal
  • If LED glows , first terminal is positive
  • If LED doesn't glow , interchange the wire connections
Battery Terminal Testing Connect LED Longer wire to terminal A Check glow Does LED light up? Identify terminal If yes, A is positive Terminal identified successfully
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