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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)
In the figure, the potentiometer wire $AB$ of length $L$ and resistance $9r$ is joined to the cell $D$ of $\mathrm{emf}$ $\varepsilon$ and internal resistance $r$. The cell $C’s$ $\mathrm{emf}$ is $\varepsilon /2$ and its internal resistance is $2r$. The galvanometer $G$ will show no deflection when the length $AJ$ is
There is a current of $1.344\, amp$ in a copper wire whose area of cross-section normal to the length of the wire is $1\,m{m^2}$. If the number of free electrons per $c{m^3}$ is $8.4 \times {10^{22}}$, then the drift velocity would be
In a potentiometer circuit a cell of $EMF$ $1.5\, {V}$ gives balance point at $36\, {cm}$ length of wire. If another cell of $EMF$ $2.5\, {V}$ replaces the first cell, then at what length of the wire, the balance point occurs ? (in $cm$)
Two resistors of resistance ${R_1}$ and ${R_2}$ having ${R_1} > {R_2}$ are connected in parallel. For equivalent resistance $R$, the correct statement is
In the circuit shown in the figure, no current flows through the ideal ammeter. If the internal resistance of the cell is negligible, the value of unknown resistance $R $ is .............. $\Omega$
Two cells of emf $2\, E$ and $E$ with internal resistance $r _{1}$ and $r _{2}$ respectively are connected in series to an external resistor $R$ (see $figure$). The value of $R ,$ at which the potential difference across the terminals of the first cell becomes zero is