In a potentiometer arrangement, a cell gives a balancing point at $75\, cm$ length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is $3: 2$, the difference in the balancing length of the potentiometer wire in above two cases will be.........$cm .$
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A potentiometer is connected between $A$ and $B$ and the balance point is obtained at $203. 6\,cm$. When the end of the potentiometer connected to $B$ is shifted to $C$, then the balance point is obtained at $24.6\,cm$. If now the potentiometer be connected between $B$ and $C$, the balance point will be at ................. $cm$
Incandescent bulbs are designed by keeping in mind that the resistance of their filament increases with the increase in temperature. If at room temperature, $100 \mathrm{~W}, 60 \mathrm{~W}$ and $40 \mathrm{~W}$ bulbs have filament resistances $\mathrm{R}_{100}, \mathrm{R}_{60}$ and $\mathrm{R}_{40}$, respectively, the relation between these resistances is
$n$ identical cells are joined in series with its two cells $A$ and $B$ in the loop with reversed polarities. $EMF$ of each shell is $E$ and internal resistance $r$. Potential difference across cell $A$ or $B$ is (here $n > 4$)
A cell of internal resistance $r$ drives current through an external resistance $R$ . The power delivered by the cell to the external resistance will be maximum when:
Resistance of a wire at $0^{\circ} \mathrm{C}, 100^{\circ} \mathrm{C}$ and $t^{\circ} \mathrm{C}$ is found to be $10 \Omega, 10.2 \Omega$ and $10.95 \Omega$ respectively. The temperature $t$ in Kelvin scale is $\qquad$
Twelve wires of equal length and same cross-section are connected in the form of a cube. If the resistance of each of the wires is $R$, then the effective resistance between the two diagonal ends would be
Four wires of the same diameter are connected in turn between two points, maintained at a constant potential difference. Their resistivities are; $\rho $ and $L$ (wire $1$ )., $1.2\,\rho $ and $1.2\,L$ (wire $2$ ), $0.9\,\rho $ and $0.9\,L$ (wire $3$ ) and $\rho $ and $1.5\,L$ (wire $4$ ). Rank the wires according to the rates at which energy is dissipated as heat, greatest first