Laws of Magnetism

Magnetism is a force that pulls or pushes objects made of certain metals like iron, nickel, and cobalt. A magnet has two ends called poles-North and South. Opposite poles attract each other, and like poles repel (push away) each other.

• The force created by a magnet is called magnetic force. This force can act from a distance without touching the object. 
• Magnetic force can move or lift objects, showing that it is a type of energy.
• In factories, ports, or garbage depots, cranes with powerful magnets are used to lift and move heavy metal objects like cars or metal scraps.

1. Aim: To magnetise a steel bar using the single-touch and double-touch methods and compare the magnetism produced by both methods.

2. Requirements: steel bar, bar magnet(s), iron filings, and thread.

3. Procedure

I. Single-Touch Method

• Place the steel bar AB on a table.
• Take a bar magnet and place its N pole on the A end of the steel bar.
• Drag the magnet towards the B end and then lift it.
• Repeat the process 15-20 times.
• Now bring the steel bar near iron filings and observe.
• Hang the bar freely on a thread and observe its behaviour.

Observation: The steel bar shows weak magnetism for a short period.

II. Double-Touch Method

• Place the steel bar on a table.
• Take two bar magnets. Place opposite poles (e.g., N of one magnet, S of the other) at the centre of the steel bar.
• Drag one magnet to the A end and the other to the B end of the bar.
• Repeat the process 15-20 times.
• Now bring the steel bar near iron filings and observe.

Observation: The steel bar shows stronger magnetism that lasts longer than the single-touch method.

4. Conclusion

• Single-Touch Method: produces weak and short-lasting magnetism.
• Double-Touch Method: produces stronger and longer-lasting magnetism.
  This experiment shows that different methods of magnetisation affect the strength and duration of the magnetic properties.