Single Choice

A charged particle goes undeflected in a region containing electric and magnetic fields. It is possible that

A$$\vec E\parallel \vec B, \vec v\parallel \vec E$$
B$$\vec E$$ is parallel to $$\vec B$$
C$$\vec v\parallel \vec E$$ also $$\vec E$$ is not parallel to $$\vec B$$
Correct Answer
D$$\vec E\parallel \vec B$$ but $$\vec v$$ is not parallel to $$\vec E$$

Solution

If the magnetic force on the particle is zero, a charged particle goes undeflected in a region containing electric and magnetic fields and $$\vec v \parallel \vec E$$. Also, $$\vec E$$ is not parallel to $$\vec B$$.


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