The term galvanometer is used to refer to a meter which can measure small currents, usually in the mA (10-3A) or mA (10-6A) range. When a soft iron core is used, the magnetic field lines tend to crowd through the core. It is because soft iron core is ferromagnetic in nature. As a result, the strength of the magnetic field due to the field magnet increases, which in turn increases the sensitivity of the galvanometer.
An electromagnet needs an electric current flowing through a coil of wire to generate a magnetic field. The strength of the magnetic field can be controlled by adjusting the amount of current flowing through the coil and the number of turns in the wire coil.
A coil of wire or a coil in the shape of a cylinder is a typical shape for an electromagnet. The strength of the magnetic field of an electromagnet can be increased significantly if the coil is wrapped around an iron core. This does not happen with nonmagnetic materials such as wood or aluminum or rubber. The enhancement of the electromagnet is caused by the magnetic properties of iron. The atoms of iron have magnetic properties as a consequence of thier electronic structure. (The cause of magnetism at the atomic level is a complex issue if described in detail and that complexity is beyond this explanation.) In a simplified picture one can say that at the atomic level the iron atoms act like little magnets. The magnetic characteristics of iron are such that an external magnetic field causes the rearrangement of the electronic structure of the iron at the atomic level and that creates a magnetization in the iron. That magnetizations has its own magnetic field just like a normal permanent magnet. The field created by the magnetization of the material adds to the external field and one gets a stronger magnetic field in and around the iron core.
An electromagnet uses electricity to create the magnetic field. Moving charges create magnetic fields. Knowing that, if we have a lot of copper wire (with a suitable insulator) wrapped around an iron core, we can send direct current through that wire, and it will create a magnetic field. The magnetic field will magnetize the iron core, and the core becomes a magnet. Wrapping wire around a nail and connecting a battery to the ends of the wire will make a simple electromagnet.
No, aluminum is not suitable for use as a core in an electromagnet because it is not a ferromagnetic material. Electromagnets require a ferromagnetic core (such as iron or steel) to enhance magnetic induction and maintain magnetism when current is flowing through the coil.
The outer core is made up of liquid iron and nickel.
A cylindrical core of soft iron is used in a moving coil galvanometer because soft iron has high magnetic permeability, meaning it enhances the magnetic field produced by the coil. This helps increase the sensitivity and responsiveness of the galvanometer to small currents passing through the coil.
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A moving iron galvanometer is a type of electrical measuring instrument that uses a coil of wire and a movable iron needle to detect and measure electric currents. When current flows through the coil, it creates a magnetic field that moves the iron needle, which indicates the strength and direction of the current.
Principle of Working:A Moving Coil Galvanometer works on the Electromagnetic effect of current carrying coil (free to move) being placed in an air-gap between the soft iron core and the strong pole pieces of the magnet.The current following in the moving coil which is the specimen to be sensed or measured results in a generation of a Magnetic Field which is opposite to that of the fixed magnetic pole pieces. And as like poles attract each other results in a generation of small deflecting torque which further deflects the pointer or the mirror attached to the axis of the coil.Construction:Moving Coil:The Moving coil which is free to move is being suspended from a soft metallic (non-magnetic) strip carrying the current specimen which is to be sensed or measured. The Moving coil is being suspended in the air-gap available between the fixed Soft Iron-Core and the fixed pole pieces of the magnet.The Soft Iron Core is used to provide a path of low reluctance so as to focus the magnetic field generated by the fixed magnetic pole pieces towards the moving coil. The use of low reluctance Soft Iron-Core helps to increase the sensitivity of the Galvanometer as well.In many of the Moving Coil Galvanometer Construction Soft Iron-Core pieces are removed and this results in the reduction of the sensitivity of the Galvanometer as a whole. In absence of the soft fixed iron core in the middle of the coil the coil then is narrowed in order to reduce the free air space, this narrowing of the coil results in the reduction of the Moment of Inertia(MI) of the moving coil arrangement. This results in having a good near to critical damping with very less oscillations.The Moving coil consists of a large number of turns wounded on a former which can either be in rectangular or circular in shape. The current carrying coil is made up of a thin non magnetic metal so as to have low resistance and less mass.Damping:Damping in Moving Coil Galvanometer is provided by an Eddy current damping mechanism. The damping is made as such to have a nearly critical damping by setting the device to be between under-damped and critical damped case.Controlling Torque:Spring Control mechanism is largely utilized to provide the suitable controlling torque.
The concave pole pieces focus the magnetic field onto the coil, enhancing sensitivity. The soft-iron cylinder helps to guide the magnetic field lines, allowing for efficient interaction with the coil. Both components work together to improve the performance and accuracy of the moving-coil galvanometer.
A moving coil Galvanometer consists of a coil PQRS which is wound over a non metalic frame having soft iron core in the middle. This Coil Is suspended in b/w a powerful magnet poles N-S with the help of Phosphor Bronze wire. Concave mirror is fixed on d suspending thread upside the coil through which deflection can b noted by Lamp and Scale arrangement. The lower end of the coil is connected by hair spring.
The soft iron core in an electromagnet enhances the magnetic field strength by concentrating and directing the magnetic flux. It increases the magnet's ability to attract and hold magnetic materials, making it more effective in applications like electric motors, generators, and transformers.
Moving coil galvanometer? If so, it is effectively an electric motor acting against a spring. the force from the motor is proportional to the current and the force from the spring is proportional to displacement. When they are equal, the needle (attached to the motor), stops. Moving iron meters rely on opposite magnetic poles repelling.
Different b/w a moving coil instrument and a moving iron instrument
A relay.
A relay.
Permanent magnet moving coil (PMMC) instruments use a moving coil that is suspended between the poles of a permanent magnet, whereas moving iron instruments use a stationary coil and a moving iron piece that moves within the coil's magnetic field. PMMC instruments are more accurate but have limited range, while moving iron instruments are less accurate but can measure higher currents. PMMC instruments are inherently more expensive compared to moving iron instruments.