A strong magnetic field is applied along the direction of the velocity of an electron. The electron would move

Question

A strong magnetic field is applied along the direction of the velocity of an electron. The electron would move along:

Accepted Answer

1.  **Identify Formula:** The magnetic force ($\mathbf{F}$) experienced by a charged particle moving with velocity $\mathbf{v}$ in a magnetic field $\mathbf{B}$ is given by the Lorentz force formula:
    $$\mathbf{F} = q(\mathbf{v} 	imes \mathbf{B})$$
    The magnitude of this force is $F = qvB \sin	heta$, where $	heta$ is the angle between the velocity vector and the magnetic field vector.
2.  **Analyze Conditions:** The problem states that the magnetic field is applied **along the direction of the velocity**. This implies that the angle $	heta$ between $\mathbf{v}$ and $\mathbf{B}$ is $0^\circ$ (parallel) or $180^\circ$ (anti-parallel).
3.  **Calculate Force:**
    Since $\sin(0^\circ) = 0$ and $\sin(180^\circ) = 0$, the magnetic force on the electron is zero:
    $$F = qvB(0) = 0$$
4.  **Conclusion:** Since no magnetic force acts on the electron, its state of motion remains unchanged (Newton's First Law). Therefore, it continues to move along its **original path** (straight line) with constant velocity.

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