The current through the ammeter shown in figure is $1 \mathrm{A}.$ If each of the$4\mathrm{\Omega }$ resistor is replaced by $2\mathrm{\Omega }$ resistor, the current in circuit will become nearly :

The ammeter shown in figure consists of a$480 \mathrm{\Omega }$coil connected in parallel to a $20 \mathrm{\Omega }$ shunt. Find the reading of the ammeter.

The meter-bridge wire $AB$shown in figure is $50 \mathrm{cm}$ long. When $AD=30 \mathrm{cm}$, no deflection occurs in the galvanometer. Find$R$.

In the given circuit, no current is passing through the galvanometer. If the cross-sectional diameter of the wire $AB$ is doubled, then for null point of galvanometer, the value of $AC$ would be

In the circuit shown, $\mathrm{P} \ne \mathrm{R},$ the reading of the galvanometer is same with switch $\mathrm{S}$ open or closed. Then

Salt water contains $n$ sodium ions $\left({\mathrm{Na}}^{+}\right)$ per cubic meter and $n$ chloride ions $\left({\mathrm{Cl}}^{–}\right)$ per cubic meter. A battery is connected to metal rods that dip into a narrow pipe full of salt water. The cross-sectional area of the pipe is $A$. The magnitude of the drift velocity of the sodium ions is $V_{\mathrm{Na}}$  and the magnitude of the drift velocity of the chloride ions is $V_{\mathrm{Cl}}$, Assume that $V_{\mathrm{Na}}>V_{\mathrm{Cl}}$ (${}^{+}\mathrm{e}$ is the charge of a proton). What is the magnitude of the ammeter reading?