Magnetism and Magnetic Field – Experiments

Introduction 

Magnetic Force:  

Magnetic force is the force of attraction or repulsion which acts between two magnets. 

Nature of Magnetic Force: 

• Magnetic force is a non-contact force. 

• Magnetic force is sometimes attractive and sometimes repulsive. 

Magnetic Field: 

The magnetic field is the region around a magnet where the force of attraction or repulsion can be detected. 

We can study the magnetic field of a magnet using a magnetic needle. 

Explanation: 

Plotting Magnetic Field Lines 

• The magnetic field around a magnet can be detected by plotting magnetic field lines. 
• The magnetic field lines around a magnet can be observed by moving a magnetic compass around a magnet. 

Magnetic Field Lines 

• Magnetic field lines are the imaginary lines around a magnet along which the north pole of a magnetic compass needle tends to move. 
• Magnetic field lines are used to show the direction of magnetic force. 

Properties of Magnetic Field Lines: 

• The magnetic field lines emerge at the north pole and merge at the south pole. 
• The magnetic field lines are very close at the poles where the magnetic field is strong. 
• The magnetic field lines do not intersect each other. 
• The relative strength of the magnetic field is shown by the degree of closeness of the field lines; the closer the line, the stronger the field. 

Different patterns of Magnetic Field Lines: 

Magnetic Field of a Bar Magnet 

Magnetic Field of a Horseshoe Magnet 

Magnetic Field of two Bar Magnet having like unlike poles towards each other 

Magnetic Field of two Bar Magnet having like poles towards each other 

Oersted’s Experiment: 

In the year 1820, Hans Christian Oersted discovered the magnetic effect of electric current. Oersted recorded the following observations. 

• If a magnetic compass is placed near a conductor carrying current wire, the needle is deflected. 
• If the direction of the current is changed, the needle shows deflection in just the opposite direction. 
• When there is no current in the current-carrying wire, the needle shows no deflection. 

Conclusion of Oersted’s Experiment: 

A current-carrying conductor creates a magnetic field around it. This magnetic field exerts a magnetic force on the magnetic needle, due to which it gets deflected. Oersted’s experiment proves that a current-carrying conductor is always associated with a magnetic field. 

Summary

• Magnetic Field: The region around a magnet where the force of attraction or repulsion can be detected is called the magnetic field.
• the magnetic field lines around a magnet can be observed by moving a magnetic compass around a magnet.
• Properties of Magnetic Field lines:
• The magnetic field lines emerge at the north pole and merge at the south pole.
• The magnetic field lines are very close at the poles where the magnetic field is strong.
• The magnetic field lines do not intersect with each other.
• The relative strength of the magnetic field is shown by the degree of closeness of the field lines; the closer line, the stronger the field.
• In the year 1820, Hans christian oersted discovered the magnetic effect of electric current.
• Oersted’s Experiment Findings:
• If a magnetic compass is placed near a conductor carrying current wire, the needle is defected.
• If the direction of the current is changed, the needle shows deflection in just the opposite direction.
• When there is no current in the current carrying wire , the needle shows no deflection.
• A current- carrying conductor has a magnetic field around it.