Directions: In the following questions, A statement of Assertion (A) ...
Galvanometer to ammeter conversion takes place by connecting a low value resistance known as “shunt” in parallel with it. The assertion is true. When two resistors are connected in parallel then the effective resistance becomes lower than the lowest value of the two resistors. Hence the reason is false.
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Directions: In the following questions, A statement of Assertion (A) ...
Assertion (A): Galvanometer to ammeter conversion takes place by connecting a low value resistance in parallel with it.
Reason (R): The low value resistance increases the effective resistance and protects the galvanometer.
Explanation:
To convert a galvanometer into an ammeter, a low value resistance is connected in parallel with it. This is done to increase the range of the galvanometer so that it can measure larger currents. Let's understand this in detail:
Galvanometer:
A galvanometer is a device used to detect and measure small electric currents. It consists of a coil of wire suspended in a magnetic field. When a current flows through the coil, it experiences a torque that causes it to deflect. The deflection of the coil is proportional to the current passing through it.
Conversion to Ammeter:
To convert a galvanometer into an ammeter, a low value resistance (known as a shunt resistor) is connected in parallel with it. The shunt resistor provides a low resistance path for the current to bypass the galvanometer coil. This allows most of the current to flow through the shunt resistor, while only a small fraction of the current passes through the galvanometer coil.
Increased Effective Resistance:
When the shunt resistor is connected in parallel with the galvanometer, the total resistance of the circuit decreases. This is because the shunt resistor has a much lower resistance compared to the galvanometer coil. As a result, the effective resistance of the circuit increases.
Protection of the Galvanometer:
The low value shunt resistor protects the galvanometer from being damaged by large currents. Since the shunt resistor provides a low resistance path, most of the current bypasses the galvanometer coil. This ensures that only a small fraction of the total current flows through the galvanometer, preventing it from being overloaded.
Conclusion:
In summary, connecting a low value resistance in parallel with a galvanometer increases its effective resistance and protects it from damage when used as an ammeter.