$A$ battery of $emf$ $10\,V$ is connected to resistances as shown in the figure. The potential difference between $A$ and $B$,$(V_A - V_B)$ is ................ $V$.

Two resistances of $400 \Omega$ and $800 \Omega$ are connected in series with a $6 \text{ V}$ battery of negligible internal resistance. $A$ voltmeter of resistance $10000 \Omega$ is used to measure the potential difference across the $400 \Omega$ resistor. The error in the measurement of potential difference in volts is approximately:

When subjected to a voltage of $10 \, V$, the current through a resistor at a temperature of $40^{\circ} C$ is $0.1 \, A$. The temperature coefficient of resistance of the material of the resistor is $2 \times 10^{-4} {}^{\circ} C^{-1}$. The temperature of the resistor in ${}^{\circ} C$ when the current drops to $0.098 \, A$ is

$A$ uniform wire of resistance $9 \, \Omega$ is cut into $3$ equal parts. They are connected in the form of an equilateral triangle $ABC$. $A$ cell of $e.m.f.$ $2 \, V$ and negligible internal resistance is connected across $B$ and $C$. The potential difference across $AB$ is ............... $V$.

$A$ $5\ V$ battery with internal resistance $2\,\Omega$ and a $2\,V$ battery with internal resistance $1\,\Omega$ are connected to a $10\,\Omega$ resistor as shown in the figure. Find the current through the $10\,\Omega$ resistor.

The current in the following circuit is ........... $A$.