A cell of emf $E$ having an internal resistance$\mathit{ }r$ is connected to an external resistance $R$. The potential difference $V$ across the resistance $R$ varies with $R$ as shown in figure by the curve :

In a circuit shown in figure resistances $R_1$ and $R_2$are known, as well as emf’s $E_1$ and $E_2$. The internal resistances of the sources are negligible. At what value of the resistance $R$ will the thermal power generated in it be the highest ?

The equivalent resistance between $A$ and $B$ will be (in $\mathrm{\Omega }$)

A wire is in the form of a tetrahedron. The resistance of each edge is $r.$ The equivalent resistances between corners $1–2$ and $1–3$ are respectively-

The equivalent resistance between points $A$ and $B$ is: 

In the question find the resistance between points $1 - 3.$

The effective resistance between points $P$ and $Q$ of the electrical circuit shown in the figure is:

A $100 \mathrm{W}$ bulb $B_1$ and two $60 \mathrm{W}$ bulbs $B_2$ and $B_3$are connected to a $250 \mathrm{V}$source as shown in the figure. Now $W_1$, $W_2$ and $W_3$ are the output powers of the bulbs $B_1$, $B_2$ and $B_{3 }$respectively. Then: