Question

Which one of the following is not correct about Lorentz Force?

• A. In presence of electric field $\vec{E}\left(r\right)$ and magnetic field $\vec{B} \left(r\right)$ the force on a moving electric charge is $\vec{F}=q \left[\vec{E} \left(r\right)+\vec{v}\times\vec{B}\left(r\right)\right]$.
• B. The force, due to magnetic field on a negative charge is opposite to that on a positive charge
• C. The force due to magnetic field becomes zero if velocity and magnetic field are parallel or anti -parallel
• D. For a static charge the magnetic force is maximum

Answer 1

Answer: (D)

If charge is not moving then the magnetic force is zero
Since $\vec{F}_{m} =q\left(\vec{V}\times\vec{B}\right)$
As $\vec{v}=0$, for stationary charge
$\therefore \vec{F}_{m}=0$