An element \(\Delta l=\Delta x \hat{i}\) is placed at the origin and carries a large current of \(I=10\) A (as shown in the figure). What is the magnetic field on the \(y\text-\)axis at a distance of \(0.5\) m? (\(\Delta x=1~\text{cm}\))
       

         
1. \(0\)
2. \(1.2\times 10^{-4}~\text{T}\)
3. \(2.1\times 10^{-4}~\text{T}\)
4. None of these

A straight wire carrying a current of 12 A is bent into a semi-circular arc of radius 2.0 cm as shown in the figure. Consider the magnetic field B at the centre of the arc. What is the magnetic field at centre due to the semi-circular loop?

$1. 0$
$2. 3.8\times {10}^{-4} T$
$3. 1.9\times {10}^{-4} T$
$4. 2.9\times {10}^{-4} T$