Question

In the case of bar magnet, lines of magnetic induction (a) Start from the North pole and end at the South pole (b) Run continuously through the bar and outside (c) Emerge in circular paths from the middle of the bar (d) Are produced only at the North pole like rays of light from a bulb.

Short answer

The correct statements about lines of magnetic induction in the case of a bar magnet are: (a) They start from the North pole and end at the South pole, and (b) They run continuously through the bar and outside, forming closed loops.

Step-by-step solution

Recall the properties of magnetic field lines

Magnetic field lines, or lines of magnetic induction, are used to visualize the magnetic field around a magnet. The following are the general properties of magnetic field lines: 1. Magnetic field lines never intersect each other. 2. They always form closed loops. 3. They emerge from the North pole and enter the South pole of the magnet. 4. The density of the magnetic field lines indicates the strength of the magnetic field. Now, let's analyze each statement in the given exercise and determine which one is correct.

Analyze statement (a)

"Start from the North pole and end at the South pole." This statement is correct. As we mentioned in the properties of magnetic field lines, they emerge from the North pole and enter the South pole of the magnet.

Analyze statement (b)

"Run continuously through the bar and outside." This statement is also correct. Magnetic field lines form closed loops, which means that they must pass through the magnet and continue outside.

Analyze statement (c)

"Emerge in circular paths from the middle of the bar." This statement is incorrect. Magnetic field lines emerge from the North pole, not the middle of the bar.

Analyze statement (d)

"Are produced only at the North pole like rays of light from a bulb." This statement is incorrect. Magnetic field lines emerge from the North pole but enter the South pole. They are not only produced at the North pole.

Conclusion

Based on our analysis, the correct statements are: (a) Start from the North pole and end at the South pole. (b) Run continuously through the bar and outside.

Key concepts

Bar Magnet

A bar magnet is a simple yet fascinating object used to demonstrate magnetic effects. It is typically a rectangular piece of material that behaves like a magnet. Each bar magnet has two poles: a North pole and a South pole. These poles are regions where the magnetic effects are strongest. When suspended freely, a bar magnet will align itself along the north-south direction of the Earth due to its magnetic field.

Bar magnets are used in various applications including compass needles, magnetic therapy, and educational demonstrations. Their consistent magnetic field makes them an excellent tool to help visualize magnetic field lines.

• Bar magnets can attract or repel other magnets, depending on the orientation of their poles relative to each other.
• They can also attract ferromagnetic materials like iron and nickel.

Understanding the basics of a bar magnet is crucial for grasping more complex magnetic phenomena.

Magnetic Induction

Magnetic induction refers to the process by which a magnetic field induces a magnetic effect in a material or space. It is also known as magnetic flux lines or simply magnetic field lines. These lines offer a way to visualize the strength and direction of a magnetic field.

When considering a bar magnet, the concept of magnetic induction helps us understand how the magnetic field is structured around it. Lines of magnetic induction emerge from the North pole and loop back through the South pole, forming closed loops both inside and outside the magnet. Iron filings sprinkled around a magnet can visibly demonstrate these lines, providing insight into the magnetic field's pattern and strength.

• The density of magnetic field lines is directly proportional to the strength of the magnetic field: more lines indicate a stronger field.
• Magnetic induction is fundamental in explaining how compasses work, how electric motors generate force, and why some materials become magnetized.

Thus, magnetic induction is a key concept in both theoretical and practical applications of magnetism.

Properties of Magnetic Field

The properties of magnetic field lines are vital for understanding magnetic phenomena. These invisible lines offer a way to model the magnetic field's direction and intensity. Here are some essential properties of magnetic field lines:

Magnetic field lines never intersect. This property is key because if they did cross, it would imply two different directions for the magnetic force at that point, which is impossible.

• Magnetic field lines always form closed loops, never having a beginning or end, except entering or exiting a magnet.
• They exit from the North pole and enter at the South pole, highlighting the unidirectional flow of magnetic influence.
• The density of these lines reflects the field's strength: dense lines indicate a stronger magnetic field and vice versa.

These properties help in predicting how magnets will interact with each other and their environment. They form the foundation for more advanced studies, like electromagnetic theory and its applications.