In a given circuit diagram, a 5 V zener diode along with a series resistance is connected across a 50 V power supply. The minimum value of the resistance required, if the maximum zener current is 90 mA will be __________ $$\Omega$$.

The total charge enclosed in an incremental volume of 2 $$\times$$ 10^$$-$$9 m³ located at the origin is ___________ nC, if electric flux density of its field is found as

D = e^$$-$$x sin y $$\widehat i$$ $$-$$ e^$$-$$x cos y $$\widehat j$$ + 2z $$\widehat k$$ C/m²

The position of the centre of mass of a uniform semi-circular wire of radius 'R' placed in x-y plane with its centre at the origin and the line joining its ends as x-axis is given by $$\left( {0,{{xR} \over \pi }} \right)$$. Then, the value of | x | is ______________.

In an electric circuit, a cell of certain emf provides a potential difference of 1.25 V across a load resistance of 5$$\Omega$$. However, it provides a potential difference of 1 V across a load resistance of 2$$\Omega$$. The emf of the cell is given by $${x \over {10}}V$$. Then the value of x is ______________.