Question

Which direction will the plotting compass point when the student places it at the north pole of one of the bar magnets? (A) Toward the magnet's north pole (B) Away from the magnet's north pole (C) Away from Earth's North Pole (D) Toward Earth's North Pole

Short answer

When placed at the north pole of a bar magnet, the compass needle will align with the magnetic field lines produced by the bar magnet and point away from the north pole of the bar magnet. Therefore, the answer is (B): Away from the magnet's north pole.

Step-by-step solution

Understand the magnetic field lines surrounding the bar magnet

When a bar magnet is present, its magnetic field lines are formed from its north pole to its south pole outside the magnet. These field lines help a compass understand the direction of the magnet's magnetic field.

Determine the direction of the compass needle when placed at the north pole of a bar magnet

When placed at the north pole of the bar magnet, the compass needle will be affected by the magnetic field produced by the bar magnet, which will dominate any influence from the Earth's magnetic field, given the close proximity. The compass will point in the direction of the magnetic field lines produced by the bar magnet. In this case, since the compass is at the north pole of the bar magnet, it will align itself with the magnetic field lines going from the north pole to the south pole of the bar magnet.

Find the answer based on the compass needle direction

As the compass needle aligns itself with the magnetic field lines when placed at the north pole of a bar magnet, it will point in the direction of the magnet's magnetic field away from the north pole of the bar magnet. This corresponds to option (B): Away from the magnet's north pole.

Key concepts

Bar Magnet

A bar magnet is a simple yet fascinating object, having two poles: the north pole and the south pole. Magnets have an invisible force field around them, known as the magnetic field. This field is what allows magnets to attract or repel each other. The magnetic field of a bar magnet is strongest at its poles. Outside the magnet, magnetic field lines flow from the north pole to the south pole.
- Bar magnets are typically made of iron, steel, or other ferromagnetic materials. - The north pole of a bar magnet is attracted to the south pole of another magnet, while like poles repel each other. Understanding how bar magnets work is essential for students exploring the basics of magnetism and its effects on objects around us.

Compass Needle

A compass needle is a small magnet that can freely rotate. Its primary role is to align itself with magnetic fields. When holding a compass, the needle naturally aligns with Earth's magnetic field, pointing towards magnetic north and south. However, when placed near another magnetic source, the compass will display the direction of this source's magnetic field instead.
- The needle of a compass is usually lightweight to allow for easy movement. - One end of the needle is marked (often in red) to indicate the north direction. This feature of compass needles is leveraged by explorers and navigators to find direction. In a scientific context, they help visualize and understand magnetic fields.

Magnetic Field Lines

Magnetic field lines are visual representations of the direction and strength of magnetic fields around an object. They provide a map of how magnetic forces exert their influence. In the case of a bar magnet, field lines emerge from the north pole, curve around, and return to enter the south pole. - The density of field lines indicates the strength of the magnetic field. - Taditionally, they are drawn closer together near the poles, where the magnetic force is strongest. Field lines never cross each other and offer insights into how magnets will interact with each other or other magnetic materials nearby. By tracing field lines, one can predict the path a compass needle will point, as it aligns with these lines.

Earth's Magnetic Field

Earth's magnetic field is like a giant magnet with an imaginary line connecting the North and South Poles. It shields the planet from cosmic and solar radiation and facilitates navigation across the globe. Interestingly, the Earth's magnetic field resembles that of a bar magnet, with field lines extending from the geographic South Pole to the geographic North Pole. - Earth has its magnetic north, which is slightly different from the geographic North Pole. - The magnetic field is not constant; it shifts over years due to changes in Earth's core. Understanding Earth's magnetic field is crucial for interpreting compass readings and for the study of geophysics. It plays a key role in enabling life by protecting the planet from harmful solar winds and radiation.