• Rectangular copper coil
• Suspension wire
• Iron core
• Pointer (needle)
• Shunt 1. U - Shaped Permanent Magnet U- shaped permanent magnet with concave poles. 2. Rectangular Copper Coil Rectangular copper coil wound on a frame of some non - magnetic material. 3. Suspension Wire Suspension wire, which also severs as current lead. Its other end is connected to a spiral which serves as second current lead. 4. Iron Core Presence of iron cylinder increases the magnetic field between the pole and the lines of forces remain parallel. 5. Pointer Aluminum pointer attached to a pivoted coil, to read the deflection. 6. Shunt It is a low value resistance connected in parallel with the coil of galvanometer. Working of Ammeter When current is allowed to pass through the galvanometer, shunt resistance which is placed parallel to the coil of the galvanometer by passes great part of the current and only a small known fraction of the total current passes through the coil of galvanometer. On passing current coil becomes magnet. Attraction or repulsion between the poles of permanent magnet and coil magnet causes a deflection in the coil, Conversion of Galvanometer into Ammeter To convert a galvanometer into ammeter, a low resistance wire called shunt is connected in parallel to galvanometer coil. Connection in Circuit An ammeter is always placed in series with other circuit components through which the current is to be measured.
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