Question

A small ball of mass m carrying a charge of Q is dropped in a uniform horizontal magnetic field B . Depth of deepest point of its path from point release is h. choose the correct option:

• A. Speed at deepest point is $\sqrt{2gh}$
• B. Speed at deepest point is $\frac{QBh}{m}$
• C. Speed at deepest point is $\frac{2mg}{QB}$
• D. Speed at deepest point is $\frac{2QBh}{m}$

Answer 1

The correct option is A Speed at deepest point is $\sqrt{2gh}$

In this contest mass $=M$, charge $=Q$ and momentum filed $=B$ height $=h$

Now, speed is independent of mass, charge and magnetic field

now,

$\frac{1}{2}m{V}^2=mgh$

$V=\sqrt{2gh}$