In the circuit shown in the figure,the ammeter reads a current of ............. $A$.

Two wires of resistance $R_1$ and $R_2$ have temperature coefficients of resistance $\alpha_1$ and $\alpha_2$,respectively. These are joined in series. The effective temperature coefficient of resistance is

Two resistances of $400 \Omega$ and $800 \Omega$ are connected in series with a $6 \text{ V}$ battery of negligible internal resistance. $A$ voltmeter of resistance $10000 \Omega$ is used to measure the potential difference across the $400 \Omega$ resistor. The error in the measurement of potential difference in volts is approximately:

In the given circuit,the terminal potential difference of the cell is: (in $ V$)

In the circuit shown,the galvanometer $G$ of resistance $60 \, \Omega$ is shunted by a resistance $r = 0.02 \, \Omega$. The current through $R$ is nearly $1 \, A$. The value of resistance $R$ (in $\Omega$) is nearly:

$A$ wire when connected to $220\,V$ mains supply has power dissipation $P_1$. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is $P_2$. Then $P_2:P_1$ is