The resistances of the four arms $P, Q, R$ and $S$ in a Wheatstone's bridge are $10\,ohm$, $30\,ohm$, $30\,ohm$ and $90\,ohm$, respectively. The e.m.f. and internal resistance of the cell are $7\,volt$ and $5\,ohm$ respectively. If the galvanometer resistance is $50\,ohm$, the current drawn from the cell will be …………… $A$

In a meter bridge experiment null point is obtained at $40\, cm$ from one end of the wire when resistance $X$ is balanced against another resistance $Y$. If $X < Y$, then the new position of the null point from the same end, if one decides to balance a resistance of $3X$ against $Y$, will be close to ………….. $cm$

For what value of unknown resistance $X$, the potential difference between $B$ and $D$ will be zero in the circuit shown in the figure …………… $\Omega$

$AB$ is a wire of uniform resistance. The galvanometer $G$ shows no current when the length $AC = 20\,cm$ and $CB = 80\, cm$. The resistance $R$ is equal to ………….. $\Omega $

In the Wheatstone's bridge (shown in figure) $X = Y$ and $A > B$. The direction of the current between ab will be