A thick metal slab carries a current I A uniform magnetic field B points perpendicular to the slab (and into the page). If point P on the slab is at a higher potential than point Q , what can we say about the charge carriers that produce the current in the slab?

Question

A thick metal slab carries a current I A uniform magnetic field B points perpendicular to the slab (and into the page). If point P on the slab is at a higher potential than point Q , what can we say about the charge carriers that produce the current in the slab?

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Answer 1

To understand the situation described, we can apply the principles of electromagnetism. Here are the steps to analyze the scenario and answer the question:

1. Identify the relevant principles: In this case, we can use the Lorentz force law, which states that the force experienced by a charged particle moving in a magnetic field is given by F = qvB, where F is the force, q is the charge of the particle, v is its velocity, and B is the magnetic field.

2. Consider the direction of the magnetic force: Since the current in the slab is perpendicular to the magnetic field, the charges that produce the current experience a force in a direction that is perpendicular to both the current and the magnetic field. This force creates a potential difference across the slab.

3. Apply the right-hand rule: To determine the direction of the force, you can use the right-hand rule. Point your thumb in the direction of the current, your index finger in the direction of the magnetic field, and your middle finger will indicate the direction of the force experienced by the charges.

4. Analyze the potential difference: Given that point P on the slab is at a higher potential than point Q, we can conclude that the charges traveling from point Q to point P experience a potential difference. This means that the force acting on the charges due to the magnetic field is in the direction from Q to P.

5. Determine the charge carriers: Based on the previous information, we can infer that the charge carriers responsible for the current in the slab are negatively charged particles (e.g., electrons) moving from point Q to point P. As they move, they experience a force due to the magnetic field, creating a potential difference.

In summary, when a thick metal slab carries a current perpendicular to a uniform magnetic field and point P on the slab is at a higher potential than point Q, we can conclude that the charge carriers responsible for the current are negatively charged particles moving from point Q to point P.