A $$12 \mathrm{~pF}$$ capacitor is connected to a $$50 \mathrm{~V}$$ battery, the electrostatic energy stored in the capacitor in $$\mathrm{nJ}$$ is

A uniform wire of diameter $$d$$ carries a current of $$100 \mathrm{~mA}$$ when the mean drift velocity of electrons in the wire is $$v$$. For a wire of diameter $$\frac{d}{2}$$ of the same material to carry a current of $$200 \mathrm{~mA}$$, the mean drift velocity of electrons in the wire is

In an electrical circuit, the voltage is measured as $$V=(200 \pm 4)$$ volt and the current is measured as $$I=(20 \pm 0.2)$$ A. The value of the resistance is:

A step up transformer is connected to an ac mains supply of $$220 \mathrm{~V}$$ to operate at $$11000 \mathrm{~V}, 88$$ watt. The current in the secondary circuit, ignoring the power loss in the transformer, is