$A$ 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?

In the circuit shown here,the readings of the ammeter and voltmeter are

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?

Shown in the figure is a semicircular metallic strip that has thickness $t$ and resistivity $\rho$. Its inner radius is $R_1$ and outer radius is $R_2$. If a voltage $V_0$ is applied between its two ends,a current $I$ flows in it. In addition,it is observed that a transverse voltage $\Delta V$ develops between its inner and outer surfaces due to purely kinetic effects of moving electrons (ignore any role of the magnetic field due to the current). Then (figure is schematic and not drawn to scale)-
$(A)$ $I = \frac{V_0 t}{\pi \rho} \ln \left(\frac{R_2}{R_1}\right)$
$(B)$ the outer surface is at a higher voltage than the inner surface
$(C)$ the outer surface is at a lower voltage than the inner surface
$(D)$ $\Delta V \propto I^2$

Two $220\; V, 100\; W$ bulbs are connected first in series and then in parallel. Each time the combination is connected to a $220\; V\; AC$ supply line. The power drawn by the combination in each case respectively will be

Suppose the drift velocity $v_d$ in a material varies with the applied electric field $E$ as $v_d \propto \sqrt{E}$. Then the $V-I$ graph for a wire made of such a material is best given by: