Question

The magnetic force acting on a charged particle of charge $-2 \mu C$ in a magnetic field of $2 T$ acting in $y$-direction, when the particle velocity is $(2 \check{ i }+3 \check{ j }) \times 10^6 ms ^{-1}$ is :

• A. 4 N in z direction
• B. 8 N in y direction
• C. 4 N in z direction
• D. 8 N in z direction

Answer 1

Answer: (D)

Force on a moving charge in magnetic field $=q(\vec{v} \times B)$
$\Rightarrow \vec{ F }=-2 \times 10^{-6}(2 \hat{ i }+3 \hat{ j }) \times 2 \hat{ j } \times 10^{6} $
$\Rightarrow \vec{ F }=-2 \times 10^{-6}(2 \hat{ i } \times 2 \hat{ j }) \times 10^{6} $
$\Rightarrow \vec{ F }=-8 \hat{ k N}$