When a proton moves along a horizontal line towards the observer, the magnetic field it produces forms anticlockwise circles around its path when viewed from the front (from the observer's perspective). This is determined using the right-hand rule: point the thumb in the direction of positive charge motion (towards you), and the curling fingers give the direction of the magnetic field.
A proton moving towards the observer creates a magnetic field that is anticlockwise (when viewed from the front).
A proton carries positive charge, so its motion constitutes a conventional current in the direction of motion.
The right-hand rule is used: thumb points in direction of current (proton motion), fingers curl in direction of B.
If current/proton comes towards you (out of page), the field is anticlockwise.
If current/proton moves away from you (into page), the field is clockwise.
For an electron (negative charge) moving towards you, the effective current is away — B becomes clockwise.
A moving proton constitutes a conventional current in the direction of its motion (since it carries positive charge).
Right-Hand Rule for magnetic field around a current:
Result: The magnetic field circles anticlockwise around the proton's path as seen by the observer.
The magnetic field produced by a moving charge:
B = (μ₀/4π) × (qv × r̂)/r²
Where:
Direction of B is given by the right-hand rule (or v × r̂ for positive charge).
Comparison:
When a proton moves towards the observer (out of the page), the magnetic field forms anticlockwise circles around the proton's path, as viewed by the observer. This is determined by the right-hand rule: thumb points towards the observer (direction of motion), and the fingers curl anticlockwise.
Point the right-hand thumb in the direction of the proton's velocity (which is also the direction of conventional current, since proton is positive). The curling fingers indicate the direction of the circular magnetic field. For a proton moving towards you, the thumb points towards you, and fingers curl anticlockwise.
For a proton (positive charge) moving towards the observer: the magnetic field is anticlockwise. For an electron (negative charge) moving towards the observer: the effective conventional current is in the opposite direction (away from observer), so the magnetic field is clockwise.
A moving charged particle constitutes an electric current. Since a proton has positive charge (+1.6 × 10⁻¹⁹ C), its motion creates a conventional current in the direction of motion. This current generates a magnetic field according to the Biot-Savart law and Ampere's law.
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