The net electric force on a charge of $$+3 \mu \mathrm{C}$$ at the mid-point on the line joining two charges of magnitude $$+2 \mu \mathrm{C}$$ and $$-2 \mu \mathrm{C}$$ separated by the distance of $$6 \mathrm{~mm}$$, is
A parallel plate capacitor of capacitance $$5 \mu \mathrm{F}$$ is charged to $$120 \mathrm{~V}$$ and then connected to another uncharged capacitor. If the potential falls to $$40 \mathrm{~V}$$, and capacitance of the second capacitor is
24 cells of emf $$1.5 \mathrm{~V}$$ each having internal resistance of $$1 \mathrm{~ohm}$$ are connected to an external resistance of $$1.5 \mathrm{~ohms}$$. To get maximum current
Two straight wires each $$10 \mathrm{~cm}$$ long are parallel to one another and separated by $$2 \mathrm{~cm}$$. When the current flowing in them is $$30 \mathrm{~A}$$ and $$40 \mathrm{~A}$$ respectively, the force experienced by either of the wires is