What is the current in $A$ flowing through $BD$ in the given circuit?

In the figure shown,the current in the $10 \, V$ battery is close to

In the circuit shown,what is the potential difference $V_{PQ}$?

The Wheatstone bridge shown in the figure gets balanced when the carbon resistor used as $R_1$ has the colour code (Orange,Red,Brown). The resistors $R_2$ and $R_4$ are $80 \, \Omega$ and $40 \, \Omega$,respectively. Assuming that the colour code for the carbon resistors gives their accurate values,the colour code for the carbon resistor used as $R_3$ would be

$ABCD$ is a square where each side is a uniform wire of resistance $1\,\Omega$. $A$ point $E$ lies on $CD$ such that if a uniform wire of resistance $1\,\Omega$ is connected across $AE$ and a constant potential difference is applied across $A$ and $C$,then $B$ and $E$ are equipotential.

If the Wheatstone bridge with four resistors $R_1, R_2, R_3$ and $R_4$ is balanced,then the correct expression is