Find the equivalent resistance between points $A$ and $B$ in the network of resistors,each of resistance $r \Omega$.

In the following circuit diagram,$E = 4\,V, r = 1\,\Omega$ and $R = 45\, \Omega$,then the reading of the ammeter $A$ will be

Two batteries of e.m.f. $4\,V$ and $8\,V$ with internal resistances $1\,\Omega$ and $2\,\Omega$ are connected in a circuit with a resistance of $9\,\Omega$ as shown in the figure. The current and potential difference between the points $P$ and $Q$ are

$A$ part of a circuit is shown in the figure. All the ammeters are ideal. If the reading of ammeter $A_1$ is $1.0 \ A$,then:

Two resistors of $100 \ \Omega$ and $200 \ \Omega$ are connected in series with a battery of $4 \ V$ and negligible internal resistance. $A$ voltmeter is used to measure the voltage across the $100 \ \Omega$ resistor,which gives a reading of $1 \ V$. The resistance of the voltmeter must be . . . . . . $\Omega$.

The equivalent resistance of the infinite network given below is: