In the diagram shown, the reading of voltmeter is $20\, V$ and that of ammeter is $4\, A$. The value of $R$ should be (Consider given ammeter and voltmeter are not ideal)
AEqual to $5\,\Omega $
BGreater from $5\,\Omega $
CLess than $5\,\Omega $
DGreater or less than $5\,\Omega $ depends on the material of $R$
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$10\,Cells$, each of emf $'E'$ and internal resistance $'r'$, are connected in series to a variable external resistance. Figure shows the variation of terminal potential difference of their combination with the current drawn from the combination.$Emf$ of each cell is ............. $V$
Potential difference across a cell and current through a cell is shown in graph. A battery consists of such identical $40$ cells. Max current supplied by the battery through a load of $2.5\,\Omega $ equal to .............. $A$
In an aluminium $(A1)$ bar of square cross section, a square hole is drilled and is filled with iron ( $Fe$ ) as shown in the figure. The electrical resistivities of $A 1$ and $Fe$ are $2.7 \times 10^{-8} \ \Omega m$ and $1.0 \times 10^{-7} \ \Omega m$, respectively. The electrical resistance between the two faces $P$ and $Q$ of the composite bar is
The potential gradient along the length of a uniform wire is $10\,volt/metre$. $B$ and $C$ are the two points at $30\,cm$ and $60\,cm$ point on a meter scale fitted along the wire. The potential difference between $B$ and $C$ will be ............. $volt$
The e.m.f. of a cell is $E\, volts$ and internal resistance is $r$ $ohm$. The resistance in external circuit is also $r$ $ohm$. The p.d. across the cell will be
In figure shows a rectangular block with dimensions $x,\, 2x$ and $4x$. Electrical contacts can be made to the block between opposite pairs of faces (for example, between the faces labelled $A-A, B-B$ and $C-C$). Between which two faces would the maximum electrical resistance be obtained ($A-A$ : Top and bottom faces, $B-B$ : Left and right faces, $C-C$ : Front and rear faces)
A current of $5\; {A}$ is passing through a non-linear magnesium wire of cross-section $0.04\; {m}^{2}$. At every point the direction of current density is at an angle of $60^{\circ}$ with the unit vector of area of cross-section. The magnitude of electric field at every point of the conductor is ....${V} / {m}$ (Resistivity of magnesium is $\rho=44 \times 10^{-8}\, \Omega m$)