How does a hot wire ammeter measures an alternating current?

1.	How does a hot wire ammeter measures an alternating current?
Answer» As the name suggests the heating effect of current is used for measuring an a.c. by a hot wire ammeter. The unknown current is allowed to pass through the metallic wire (of the ammeter) that gets expanded due to heating effect and this expansion is converted into certain deflection of a pointer on a scale-both being inside the hot wire ammeter. If Q be the quantity of heat produced and be the value of the (unknown) current then, Q ∝ I² The expansion in the wire is also proportional to the square of the current. It is clear that direction of the flow of the current immertial. In a.c. the heat produced in wire through which the current flows depends only on the magnitude and not on the direction of the current flowing. This is the reason that a hot wire ammeter measured are a.c.

Answer»

As the name suggests the heating effect of current is used for measuring an a.c. by a hot wire ammeter. The unknown current is allowed to pass through the metallic wire (of the ammeter) that gets expanded due to heating effect and this expansion is converted into certain deflection of a pointer on a scale-both being inside the hot wire ammeter. If Q be the quantity of heat produced and be the value of the (unknown) current then,

Q ∝ I²

The expansion in the wire is also proportional to the square of the current. It is clear that direction of the flow of the current immertial. In a.c. the heat produced in wire through which the current flows depends only on the magnitude and not on the direction of the current flowing. This is the reason that a hot wire ammeter measured are a.c.

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