Cells, EMF, Internal Resistance

The reading on a high resistance voltmeter, when a cell is connected across it, is $2.0V$. When the terminals of the cell are also connected to a resistance of  $3 \Omega$  as shown in the circuit, the voltmeter reading drops to $1.5V$. The internal resistance of the cell is :

Two identical cells each of emf $2$ Volts are connected in parallel and the combination is connected across a resistor of resistance $10 \mathrm{\Omega }$. An ammeter connected between the resistor and the cell combination gives the reading of $\frac{1}{6}$ Amperes. The internal resistance of each cell is

Five cells each of emf$E$ and internal resistance $r$ are connected in series. Due to oversight one cell is connected wrongly. The equivalent internal resistance of the combination is

Calculate internal resistance $r$ in the following circuit.

What is the total potential difference between them?

A current of $2 \mathrm{A}$ flows through a $2 \mathrm{\Omega }$ resistor when connected across a battery. The same battery supplied a current of $0.5 \mathrm{A}$ when connected across a $9 \mathrm{\Omega }$ resistor. The internal resistance of the battery is

Two sources of equal emfs are connected in series. This combination is connected to an external resistance $R$. The internal resistances of the two sources are $r_1$ and $r_2\left(r_1>r_2\right)$. If the potential difference across the source of internal resistance $r_1$ is zero then the value of $R$ will be

What is the internal resistance of a battery if its emf is $6 \mathrm{V}$ and the potential difference across its terminals is $5.8 \mathrm{V}$ when a current of $0.50 \mathrm{A}$ flows in the circuit when it is connected across a load?

For the circuit shown in figure, if voltmeter reads $1.2 \mathrm{V}$, then find the value of $r$

Two identical cells each of emf $1.5 \mathrm{V}$ are connected in parallel across a parallel combination of two resistors each of resistance $20 \mathrm{\Omega }$. A voltmeter connected in the circuit measures $1.2 \mathrm{V}$. The internal resistance of each cell is :

If a cell of constant E.M.F. produces the same amount of the heat during the same time in two independent resistors $R_1$ and $R_2$, when they are separately connected across the terminals of the cell, one after the another, find the internal resistance of the cell.

What is meant by electro motive force ?

A cell of $\mathrm{e}\mathrm{m}\mathrm{f}\mathrm{ }E$ and internal resistance $r$ is connected in series with an external resistance $nr$ . Then, the ratio of the terminal potential difference to $\mathrm{e}\mathrm{m}\mathrm{f}$ is $\frac{n}{n+\alpha }$. Write the value of $\alpha$.

What is the emf of a cell?

How is potential difference generated across the terminals of a cell?

When the terminals of a cell are shorted potential difference across the terminals is zero or short circuited?

Derive the potential difference across the terminals of a cell when circuit is open.

Derive the potential difference across the terminals of a cell when current is being drawn from it.

Explain internal resistance of a cell. What happens if there is zero resistance in the circuit?