The heat evolved or absorbed at the junction when an electric current passes through the junction of two different metals is known as which effect?

Two electric bulbs marked $40\,W, 220\,V$ and $60\,W, 220\,V$ are connected in series across a $220\,V$ supply,resulting in an effective power $P_1$. When they are connected in parallel across the same $220\,V$ supply,the effective power is $P_2$. The ratio $\frac{P_1}{P_2}$ is:

$A$ battery consists of a variable number $n$ of identical cells,each having electromotive force $E$ and internal resistance $r$,connected in series. The terminals of the battery are short-circuited,and the current $I$ is measured. Which one of the graphs below shows the relationship between $I$ and $n$?

Ten $60 \, W, 220 \, V$ bulbs are connected in series to a $220 \, V$ supply. The power consumed in the circuit is ......... $W$.

If the internal resistance of a cell is proportional to the current drawn from the cell,then the best representation of the terminal potential difference of the cell with respect to the current drawn from the cell will be:

Two heating coils, one of fine wire and the other of thick wire of the same material and of the same length, are connected in series and in parallel. Which of the following statements is correct?