A constant voltage of 50 V is maintained between the points $A$ and $B$ of the circuit shown in the figure. The current through the branch $C D$ of the circuit 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
A uniform metal wire of length $$l$$ has $$10 \Omega$$ resistance. Now this wire is stretched to a length $$2l$$ and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is
The given circuit shows a uniform straight wire $$A B$$ of $$40 \mathrm{~cm}$$ length fixed at both ends. In order to get zero reading in the galvanometer $$G$$, the free end of $$J$$ is to be placed from $$B$$ at:
