Define the current sensitivity of a galvanometer. Write S.I unit.

Figure shows two circuits each having a galvanometer and a battery of 3V. When the galvanometer in each arrangement does not show any deflection, obtain the ratio R1/R2.

The current sensitivity of a galvanometer refers to its ability to detect and respond to a small amount of current passing through it. It is typically measured in amperes per division (A/div) or microamperes per division (μA/div) on the galvanometer's scale. The current sensitivity represents the amount of current required to produce a full-scale deflection on the galvanometer.

The SI unit for current sensitivity is amperes per division (A/div).

Now, let's address the problem you've described with the two circuits and the galvanometers.

In the problem, you have two circuits, each containing a galvanometer and a battery with a voltage of 3V. When the galvanometer in each arrangement does not show any deflection, it means that the current passing through the galvanometer is zero.

The relationship between voltage (V), current (I), and resistance (R) in a circuit is given by Ohm's law:

V = I * R

Since the voltage (V) is the same (3V) in both circuits, and the current (I) is zero in both cases, we can write:

3V = 0 * R1 (for the first circuit)
3V = 0 * R2 (for the second circuit)

Since the current is zero in both cases, it means that the resistance (R1 and R2) in each circuit is effectively infinite (open circuit). In other words, the galvanometers in both arrangements are connected in parallel with extremely high resistance, preventing any current from passing through them.

So, the ratio R1/R2 in this case is equal to (infinity/infinity), which is an indeterminate form. Therefore, without specific resistance values or additional information, it's not possible to determine the exact ratio R1/R2.