Two resistors of $200\ k\Omega$ and $1\ M\Omega$ form a potential divider circuit. If the potentials at the two ends are $+3\ V$ and $-15\ V$,the voltage at the junction will be ............... $V$.

Two resistors of $100 \ \Omega$ and $200 \ \Omega$ are connected in series with a battery of $4 \ V$ and negligible internal resistance. $A$ voltmeter is used to measure the voltage across the $100 \ \Omega$ resistor,which gives a reading of $1 \ V$. The resistance of the voltmeter must be . . . . . . $\Omega$.

Five equal resistors,each of resistance $R$,are connected as shown in the figure below. $A$ battery of $V$ volt is connected between $A$ and $B$. The current flowing in $FC$ will be

In the given circuit,the current in each resistance is: (in $A$)

$A$ straight wire of resistance $R$ is bent into the shape of a square. $A$ cell of emf $12 \text{ V}$ is connected between two adjacent corners of the square. The potential difference across any diagonal of the square is (in $\text{ V}$)

$A$ battery of $e.m.f.$ $10 \, V$ and internal resistance $3 \, \Omega$ is connected to a resistor $R$ as shown in the figure. If the current in the circuit is $0.5 \, A$,then the resistance of the resistor $R$ will be ............. $\Omega$.