Cells in Series and in Parallel

Two cells of emf  $E_1$  and  $E_2$  and internal resistance  $r_1$  and  $r_2$ , are connected in parallel with each other. Obtain expressions for the equivalent emf and equivalent internal resistance of this parallel combination.

Two cells having the internal resistance $0.2\mathrm{ }\mathrm{\Omega }$ and $0.4\mathrm{ }\mathrm{\Omega }$ are connected in parallel. The voltage across the battery terminals is $1.5 \mathrm{V}$. The emf of first cell is $1.2 \mathrm{V}$, the emf of second cell is (in volt) $E$. Write the value of $\left[E\right],$ where $\left[ \right]$ is the greatest integer function.

In the circuit shown in figure, reading of ammeter will: 

A battery of the emf $18 \mathrm{V}$ and internal resistance of $3 \mathrm{\Omega }$ and another battery of emf $10 \mathrm{V}$ and internal resistance of $1 \mathrm{\Omega }$ are connected as shown in figure. Then the voltmeter reading is

${\mathrm{V}}_{\mathrm{A}}-{\mathrm{V}}_{\mathrm{B}}$ is

Assertion: When cells are connected in parallel to the external load, the effective e.m.f increases.

Reason: Because the effective internal resistance of the cells decreases.

Assertion: When cells are connected in parallel to the external load, the effective e.m.f. increases.

Reason: All the cells will be sending the current to the external load in the same direction.

Assertion: When cells are connected in series to the external load the effective e.m.f. increases.

Reason: The cells help each other in sending the current to the external load.

Assertion: When cells are connected in parallel to the external load, the effective e.m.f increases.

Reason: Because the effective internal resistance of the cells decreases.

Assertion: When cells are connected in parallel to the external load, the effective e.m.f. increases.

Reason: All the cells will be sending the current to the external load in the same direction.

Assertion: When cells are connected in series to the external load the effective e.m.f. increases.

Reason: The cells help each other in sending the current to the external load.

Find the net $\mathrm{e}\mathrm{m}\mathrm{f}$ of the three batteries shown in figure -

In the diagram shown find the potential at point $A$ .

The potential difference between points $A$ & $B$ in the given diagram is -

Two cells, having the same emf are connected in series through an external resistance $R$ . Cells have internal resistances $r_1$ and $r_2\mathrm{ }\left(r_1>r_2\right)$ respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of $R$ is -

Which of the following are true, when the cells are connected in series?

$n$ identical cells, each of emf $E$ and internal resistance $r$, are connected in series to a cell $A$ which is joined with reverse polarity. The potential difference across each cell, except $A$, is

Two identical cells send the same current in $3\mathrm{ }\mathrm{\Omega }$ resistance, whether connected in series or in parallel. The internal resistance on the cell should be,

Twelve cells, each having emf $E$ volts are connected in series and kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12-cell battery is connected with an ammeter, an external resistance $R \mathrm{\Omega }$ and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit, when the 12-cell battery and 2-cell battery aid each other is $3 \mathrm{A} \mathrm{and} 2 \mathrm{A}$ when they oppose each other. Then, the number of cells in 12-cell battery that are connected wrongly is,

What is the potential drop between points $A$and $C$in the following circuit? Resistances $1 \mathrm{\Omega }$and $2 \mathrm{\Omega }$represent the internal resistance of the respective cells.