For a given thermocouple,the thermo $e.m.f.$ can be

The direction of current in an iron-copper thermocouple is

$A$ battery of $6$ cells,each with an $e.m.f.$ of $2\,V$ and an internal resistance of $0.5\,\Omega$,is being charged by a $220\,V$ $D.C.$ mains using an external resistor of $10\,\Omega$. What is the charging current in $A$?

$A$ coil takes $15\,min$ to boil a certain amount of water,and another coil takes $20\,min$ for the same process. What is the time taken to boil the same amount of water when both coils are connected in series?

Two bulbs rated $(25\, W - 220\, V)$ and $(100\, W - 220\, V)$ are connected in series to a $440\, V$ line. Which one is likely to fuse?

Two current elements $P$ and $Q$ have current-voltage characteristics as shown below. Which of the graphs given below best represents the current-voltage characteristics when $P$ and $Q$ are in series?