A cell of emf 'E ’ and internal resistance 'r ’ is connected acro… - Vidyadip

Question

A cell of emf $ 'E\ ’$ and internal resistance $\ 'r\ ’$ is connected across a variable resistor $' R\ ’.$ Plot a graph showing variation of terminal voltage $' V\ ’$ of the cell versus the current $' I\ ’.$ Using the plot, show how the emf of the cell and its internal resistance can be determined.

✓

Answer

The relation between $V$ and $I$ is
$V = E – Ir$
Hence, the graph, between $V$ and $I,$ has the form shown below.

For point $A, I=0,$ Hence, $V_A= E$
For point $B, V=0,$ Hence, $E=I_Br$ Therefore, $\text{r} =\frac{\text{E}}{\text{I}_{B}}$
Alternate Answer
Emf $(E)$ equals the intercept on the vertical axis. Internal resistance $(r)$ equals the negative of the slope of the graph.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "2 Marks Questions" from Current Electricity→Current Electricity — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

Whether the diffraction effects from a slit will be more clearly visible or less clearly, if the slit-width is increased?

The mass of a nucleus in its ground state is always less than the total mass of its constituents - neutrons and protons. Explain.
Plot a graph showing the variation of potential energy of a pair of nucleons as a function of their separation.

In a Callender's compensated constant pressure air thermometer, the volume of the bulb is 1800 cc. When the bulb is kept immersed in a vessel, 200 cc of mercury has to be poured out. Calculate the temperature of the vessel.

A mass of $6 \times 10^{24}kg ($equal to the mass of the earth$)$ is to be compressed in a sphere in such a way that the escape velocity from its surface is $3 \times 10^8m/s.$ What should be the radius of the sphere?

Calculate the orbital period of the electron in the first excited state of hydrogen atom.

Explain the difference between behaviour of a conductor and a dielectric inside external electric field.

What happens to the energy of light waves in interference?

In a Michelson experiment for measuring speed of light, the distance travelled by light between two reflections from the rotating mirror is $4.8\ km.$ The rotating mirror has a shape of a regular octagon. At what minimum angular speed of the mirror $($other than zero$)$ the image is formed at the position where a non$-$rotating mirror forms it?

Write two definitions of mutual inductance. State what it depends on and state its unit and dimensional formula.

Sketch a graph showing variation of reactance of a capacitor with frequency in an AC circuit.