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:

In the circuit shown the readings of the ammeter and voltmeter are $4 \mathrm{A}$and $20 \mathrm{V}$respectively. The meters are non-ideal, then $R$ is

In the circuit shown in figure reading of voltmeter is $V_{1 }$when only $S_1$ is closed, reading of voltmeter is $V_2$ when only $S_2$ is closed and reading of voltmeter is $V_3$when both $S_1$ and $S_2$ are closed. Then 

If the reading of ammeter ${\mathrm{A}}_3$ in figure is $0.75 \mathrm{A}$. Neglecting the resistances of the ammeters, the reading of ammeter ${\mathrm{A}}_2$ will be

If the reading of ammeter ${\mathrm{A}}_3$ in figure is $0.75 \mathrm{A}$. Neglecting the resistances of the ammeters, the reading of ammeter ${\mathrm{A}}_1$ will be

The resistance of the rheostat shown in figure is $30 \mathrm{\Omega }.$ Neglecting the ammeter resistance, the ratio of minimum and maximum currents through the ammeter, as the rheostat is varied, will be