The thermo $e.m.f.$ of a thermocouple is $25\,\mu V/^{\circ}C$ at room temperature. $A$ galvanometer of $40\,\Omega$ resistance, capable of detecting current as low as $10^{-5}\,A$, is connected with the thermocouple. The smallest temperature difference that can be detected by this system is ................ $^{\circ}C$.

$A$ galvanometer of resistance $G$ is connected in a circuit. Now,a resistance $R$ is connected in series with the galvanometer. To keep the main current in the circuit unchanged,the resistance $S$ to be put in parallel with the series combination of $G$ and $R$ is:

In the given circuit,if the value of each resistor is $10\, \Omega$,then the current flowing through $AD$ will be:

An electric toaster uses nichrome for its heating element. When a negligibly small current passes through it,its resistance at room temperature $(27.0^{\circ} C)$ is found to be $75.3\; \Omega$. When the toaster is connected to a $230\; V$ supply,the current settles,after a few seconds,to a steady value of $2.68\; A$. What is the steady temperature (in $^{\circ} C$) of the nichrome element? The temperature coefficient of resistance of nichrome averaged over the temperature range involved is $1.70 \times 10^{-4}\; ^{\circ} C^{-1}$.

The equivalent resistance of the infinite network given below is:

If a $30\, V, 90\, W$ bulb is to be operated on a $120\, V$ line,what resistance in ohms should be connected in series with the bulb?