Cells in Series and in Parallel

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.

Two cells with the same emf $\epsilon$ and internal resistance $r_{1 }\& r_2$ are connected in series to an external resistance $R\mathit{.}$ The value of $R$ so that the potential difference across the first cell be zero is:

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

Derive an expression for the effective EMF and effective internal resistance of two cells connected in parallel.

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 -

The ammeter reading in the given circuit 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 -

Three batteries of emf $1 V$ and internal resistance $1\mathrm{ \Omega }$ each are connected, as shown in the figure. Effective emf of combination between the points $PQ$ is

  

Eels can generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in $100$ rows, each row stretching horizontally along the body of the fish containing $5000$ electroplaques. The arrangement is suggestively shown below. Each electroplaque has an emf of 0.15 V and internal resistance of $\text{0.25 Ω}$. What is the value of current through $\text{500 Ω}$ in given circuit?

                

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