A horizontal wire is oriented along a north-south line, and...

Name: Problem 8, Chapter 14: The Physics of Everyday Phenomena: A Conceptual Introduction to Physics
Uploaded: 2021-09-19T16:17:52-08:00
Duration: 5 min 21 s
Channel: Vishal Gupta
Description: A horizontal wire is oriented along a north-south line, and a compass is placed above it. Will the needle of the compass deflect when a current flows through the wire, and if so, in what direction? Explain.

A horizontal wire is oriented along a north-south line, and a compass is placed above it. Will the needle of the compass deflect when a current flows through the wire, and if so, in what direction? Explain.

Key Concepts

Magnetic Field Generated by a Current-Carrying Wire

When an electric current flows through a wire, it generates a magnetic field that circulates around the wire. This phenomenon is explained by Ampere's Law, which states that the magnetic field is proportional to the current and follows a circular path around the wire. The concept is central in electromagnetism and is used to understand how currents produce magnetic fields in various applications.

Right-Hand Rule

The right-hand rule is a method used to determine the direction of the magnetic field surrounding a current-carrying conductor. By pointing the thumb of the right hand in the direction of the conventional current, the curl of the fingers shows the circular direction of the magnetic field lines. This rule provides an intuitive way to visualize and predict the orientation of magnetic fields in relation to current flow.

Superposition of Magnetic Fields

The principle of superposition states that when multiple magnetic fields are present at a point, the net magnetic field is the vector sum of the individual fields. In the context of a current-carrying wire near a compass, the field produced by the wire combines with the Earth's magnetic field. The resultant field determines the orientation of the compass needle, illustrating how overlapping magnetic influences can modify the direction in which magnetic objects align.

Magnetic Torque on a Compass Needle

A compass needle is a small magnet that aligns itself along the direction of the prevailing magnetic field. When subjected to an external magnetic field, such as that from a nearby current-carrying wire, a torque is exerted on the needle, causing it to deflect until the magnetic forces are balanced. This concept of magnetic torque explains the deflection observed in the compass needle as it aligns itself with the net magnetic field generated by both the Earth and the wire.

Transcript

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