Lesson 12 of 14
The big picture
Show on a big screenOne current does two jobs. It warms a wire. It makes a magnet. A cell supplies the current.
| Idea | Remember |
|---|---|
| A wire warms up | Current warms any ordinary wire. With the same current, the harder wire warms more |
| Heat put to work | A heating element uses the warmth on purpose |
| A wire made to fail | A fuse of the right size melts first and opens the loop |
| A wire becomes a magnet | A compass swings. Turn the cell, and it swings back |
| More turns, more pull | More current, an iron core, more turns at the same current |
| A magnet you can switch off | Current off, and with an iron core the pins fall |
| A bell that rings itself | The arm breaks its own circuit |
| Two metals and a liquid | Two different metals in an electrolyte make current in a simple cell. Used up, it is dead |
| Cells that run down | A dry cell cannot be charged. A rechargeable cell can. After many rounds, it holds less |
Both effects stop when the loop opens.
Open Chapter 4, Electricity: Magnetic and Heating Effects, in your NCERT book.