Question

An electron having a charge $e$ moves with a velocity $v$ in positive $x$ direction. A magnetic field acts on it in positive $y$ direction. The force on the electron acts in (where outward direction is taken as positive z-axis).

• A. Negative direction of $y$-axis
• B. Positive direction of $y$-axis
• C. Positive direction of $z$-axis
• D. Negative direction of $z$-axis

Answer 1

Answer: (D)

$\vec{F}=-e(\vec{v}\times \vec{B})$
So using right hand thumb rule
$\vec{F}$ will be in $-z$ direction.