What is the current $I$ (in $A$) flowing through the given circuit?

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:

In the circuit shown,the energy stored in the capacitor is $n\,\mu J$. The value of $n$ is ..............

The emf of a thermocouple,one junction of which is kept at $0\,^{\circ}C$,is given by $e = at + bt^2$. The Peltier coefficient will be

What is the equivalent resistance of the circuit in $\Omega$?

When a current of $2 \ A$ flows through a conductor,$80 \ J$ of heat is produced in $10 \ s$. The resistance of the conductor is ........... $\Omega$.