Resistance is the opposition to the flow of current
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Water boils in an electric kettle in $20$ minutes after being switched on. Using the same main supply, the length of the heating element should be. . . . . . .to . . . . . .. times of its initial length if the water is to be boiled in $15$ minutes.
There are $8$ equal resistances $R$. Two are connected in parallel, such four groups are connected in series, the total resistance of the system will be
A uniform wire of resistance $20\,ohm$ having resistance $1\Omega /m$ is bent in the adjoining form of a circle as shown in the figure. If the equivalent resistance between $M$ and $N$ is $1.8 \,\Omega $, then the length of the shorter section is ................ $m$
A cell of $e.m.f.$ $1.5\,V$ having a finite internal resistance is connected to a load resistance of $2\,\Omega $. For maximum power transfer the internal resistance of the cell should be ............. $ohm$
As shown, the circuit is made of $8$ different resistors. It is found that when $R_1 = 4\,\,\Omega,$ the resistance between $A$ and $B$ is $2\,\,\Omega.$ Now replace $R_1$ by a $6\,\,\Omega$ resistor, what is the resistance between $A$ and $B$?
A potentiometer $PQ$ is set up to compare two resistances as shown in the figure. The ameter $A$ in the circuit reads $1.0\, A$ when two way key $K_3$ is open. The balance point is at a length $l_1\, cm$ from $P$ when two way key $K_3$ is plugged in between $2$ and $1$ , while the balance point is at a length $l_2\, cm$ from $P$ when key $K_3$ is plugged in between $3$ and $1$ . The ratio of two resistances $\frac{{{R_1}}}{{{R_2}}}$ is found to be