Moving-coil ammeter:

• This is the most common type and uses a galvanometer as its core component.

• A galvanometer is a sensitive instrument that detects small currents.

• It has a coil of wire suspended between the poles of a permanent magnet.

• When current flows through the coil, it interacts with the magnetic field, causing the coil to deflect.

• The deflection is proportional to the current flowing, and a pointer attached to the coil indicates the current value on a calibrated scale.

Moving-iron ammeter:

• This type uses a piece of soft iron that is attracted to a fixed electromagnet.

• The electromagnet is created by a coil of wire through which the current flows.

• The greater the current, the stronger the magnetic attraction, causing the iron piece to move.

• This movement is again linked to a pointer and calibrated scale to indicate the current.

 Points:

• Series Connection: Ammeters are always connected in series with the circuit where you want to measure the current. This ensures that the entire current flowing through the circuit also passes through the ammeter.

• Low Resistance: Ammeters are designed with very low internal resistance to minimize their impact on the circuit's current flow.

• Shunt Resistors: For measuring larger currents, a shunt resistor is connected in parallel with the moving coil. This bypasses most of the current around the coil, protecting it while still allowing the measurement of the total current.

• Moving-coil ammeters typically measure direct current (DC) only.

  
  

• Moving-iron ammeters can measure both AC and DC currents.

• Digital ammeters use electronic circuits to convert the current into a digital signal displayed on a screen.