$n$ identical cells whether joined together in series or in parallel, give the same current, when connected to an external resistance '$R$'. The internal resistance of each cell is :—

A group of N cells each of whose emf varies directly with the internal resistance as per the equation E_N = 1.5 r_N are connected as shown in the figure. The current in the circuit is :-

Eels are able to 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 electroplaques has an emf of 0.15 V and internal resistance of $0.25 \mathrm{\Omega }$. The water surrounding the eel completes a circuit between its head and its tail. If the water surrounding it has a resistance of $500 \mathrm{\Omega }$, the current an eel can produce in water is about :-

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

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

If the reading of the ammeter $A_1$ in the figure is $2.4 \mathrm{A}$. Neglecting the resistances of the ammeters, the reading of the ammeter $A_2$ will be

Two cells of emf $10 \mathrm{V} \mathrm{and} 15 \mathrm{V}$ are connected in parallel to each other between points $A \mathrm{and} B.$ The cell of emf $10 \mathrm{V}$ is ideal but the cell of emf $15 \mathrm{V}$ has internal resistance $1 \mathrm{\Omega }$. The equivalent emf between $A$ and $B$ is:

An electric current passes through non-uniform cross-section wire made of homogeneous and isotropic material. If the $j_{\mathrm{A}}$ and $j_{\mathrm{B}}$ be the current densities and $E_{\mathrm{A}}$ and $E_{\mathrm{B}}$ be the electric field intensities at $A$ and $B$, respectively, then

Figure shows a potentiometer. Length of the potentiometer wire $AB$ is $100 \mathrm{cm}$ and its resistance is $100\Omega$. EMF of the battery $E$ is $2 \mathrm{V}$. A resistance $R$ of $50\Omega$ draws current from the potentiometer. What is the voltage across $R$ when the sliding contact $C$is at the mid-point of $AB ?$