Question

A uniform magnetic field b=3i+4j+k exists in region

Answer 1

When the lines of magnetic field are actually parallel, the magnetic force experienced by the object is exactly the same at very point in the field as well as such the field is known as uniform magnetic field.  

If the uniform magnetic field b=3i+4j+k exists in region, then the value of k is calculated as 49.

Answer 2

$\Large \mathfrak{The \: \: value \: \: of \: \: \: K \: \: is \: \: 49}$