What is immaterial for an electric fuse wire?

The current from the battery in the circuit diagram shown is .............. $A$.

Two sources of equal $emf$ $E$ are connected in series to an external resistance $R$. The internal resistances of the two sources are $R_1$ and $R_2$ $(R_2 > R_1)$. If the potential difference across the source having internal resistance $R_2$ is zero,then:

If a high power heater is connected to electric mains,then the bulbs in the house become dim,because there is a

$A$ $dc$ source of $emf \, E_1 = 100 \, V$ and internal resistance $r = 0.5 \, \Omega$,a storage battery of $emf \, E_2 = 90 \, V$,and an external resistance $R$ are connected as shown in the figure. For what value of $R$ will no current pass through the battery $E_2$ (in $.5$)? ................ $\Omega$

Consider the four circuits shown in the figure given below. In which circuit is the power dissipated the greatest? (Neglect the internal resistance of the power supply)