The force on a charged particle due to electric and magnetic fields is given by $\vec{F}=q\vec{E}+q\vec{v}\times\vec{B}$. If $\vec{E}$ is along the $X$-axis and $\vec{B}$ asking the $Y$-axis, in what direction and with what minimum speed $v$ should a positively charged particle be sent so that the best force on it is $\mathrm{ZERO}$?
I have done it like: For force to be $0$, $||q\vec{v}\times\vec{B}||=0$ and has to act opposite to the direction of $q\vec{E}$ and so $||\vec{v}||=\frac{-||\vec{E}||}{||\vec{B}||\sin\theta}$.
I need to know certain things.
I understand that the velocity has to be sent in the $Z$-axis but whether it's positive $Z$ axis or negative $Z$ axis will depend on the direction of the electric and magnetic fields right?
So what should be the speed: $\frac{||\vec{E}||}{||\vec{B}||}$ right? And the velocity should be $\frac{±||\vec{E}||}{||\vec{B}||}$ along $Z$ axis right? (Depending upon positive or negative $Z$ axis?)
By any means, do we know the direction (positive or negative axis) of the velocity, electric field and magnetic field from what's mentioned in the question?
Please check my solution and if possible, do write a fair solution for me as well in the answer section.