In the given figure, an ammeter reads $5 \, A$ and a voltmeter reads $40 \, V$. The actual value of resistance $R$ is

Two wires of the same material have lengths in the ratio $1 : 2$ and radii in the ratio $2 : 1$. If they are connected in parallel to a battery,what is the ratio of heat produced in them?

The current $i$ in the circuit shown in the figure 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:

An electric current is passed through a circuit containing two wires of the same material,connected in parallel. If the lengths and radii of the wires are in the ratio of $4/3$ and $2/3$ respectively,then the ratio of the currents passing through the wires will be:

$A$ potential divider is used to give outputs of $4\,V$ and $8\,V$ from a $12\,V$ source. Which combination of resistances,$(R_1 : R_2 : R_3)$ gives the correct voltages?