In a transformer,the number of turns in the primary coil is $140$ and in the secondary coil is $280$. If the current in the primary coil is $4 \, A$,then the current in the secondary coil is ........ $A$.

The equation of the circle with radius $5$ and touching the coordinate axes in the third quadrant is

$A$ current of $2\, A$ flows in a system of conductors as shown. The potential difference $(V_A - V_B)$ will be ................ $V$.

The angle of a prism is $A$. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence $2A$ on the first surface return back through the same path after suffering reflection at the silvered surface. The refractive index $\mu$ of the prism is:

$A$ particle of mass $m$ and charge $q$ moves with a constant velocity $v$ along the positive $x$-direction. It enters a region containing a uniform magnetic field $B$ directed along the negative $z$-direction,extending from $x = a$ to $x = b$. The minimum value of $v$ required so that the particle can just enter the region $x > b$ is

Which of the following is the strongest reducing agent?