Soft iron is used to make the core of transformer because of its

Table of Contents • • • • • Why is soft iron is chosen as the material for the core of the transformer? The reason for having a soft iron core is that it is capable of producing internal magnetic flux densities some 10,000 (relative permeability) times stronger than in air. This is the basic principle of induction where, as engineers, we exploit the magnetic properties of the soft iron core material. What are the advantages of iron core in the transformer? The magnetic reluctance of iron is less so that it allows more flux through it. Heat losses are less. It is used for low frequencies (<10KHz). Why iron is chosen as the material for the core of the transformer why not we use Aluminium? The ability of iron or steel to carry magnetic flux is much greater than air. This ability to carry flux is called permeability. Thus iron core is used in transformer in place air core. This means that the ability of a steel core to carry magnetic flux is 1500 times that of air. What is produced in the iron core of a transformer? A basic transformer is made from two coils of wire, a primary coil from the alternating current (ac) input and a secondary coil leading to the ac output. The primary coil current produces a magnetic field, which changes as the current changes. The iron core increases the strength of the magnetic field. Why is soft iron preferred? Soft iron core is used in electromagnets because they get easily magnetised/demagnetised when current is flowing or not flowing along th...

In Ferrites [ ] Ferrites are ceramic compounds of the • Manganese-zinc ferrite ( MnZn, with the formula Mn aZn (1−a)Fe 2O 4). MnZn have higher • Nickel-zinc ferrite ( NiZn, with the formula Ni aZn (1−a)Fe 2O 4). NiZn ferrites exhibit higher resistivity than MnZn, and are therefore more suitable for frequencies above 1MHz. For applications below 5MHz, MnZn ferrites are used; above that, NiZn is the usual choice. The exception is with As any given blend has a trade-off of maximum usable frequency, versus a higher mu value, within each of these sub-groups, manufacturers produce a comprehensive range of materials for different applications blended to give either a high initial (low frequency) inductance or lower inductance and higher maximum frequency, or for interference suppression ferrites, an extensive frequency range, but often with a very high loss factor (low It is essential to select the suitable material for the application, as the correct ferrite for a 100kHz Applications [ ] There are two broad applications for ferrite cores that differ in size and frequency of operation: signal transformers, which are of small size and higher frequencies, and power transformers, which are of large size and lower frequencies. Cores can also be classified by shape, such as The ferrite cores used for power transformers work in the low-frequency range (1 to 200kHz usually The ferrite cores used for signals have a range of applications from 1kHz to many MHz, perhaps as much as 300MHz, a...

• In series fine wire liberates more energy while in parallel thick wire will liberate more energy • In series fine wire liberates less energy while in parallel thick wire will liberate more energy • Both will liberate equally • In series the thick wire will liberate more while in parallel it will liberate less energy Views: 5,705 3.19 EXAMPLE 29. A balloon is ascending at the rate of 9.8 ms − 1 at a height of 39.2 m above the ground when a food packet is dropped from the balloon. After how much time and with what velocity does it reach the ground? Take g = 9.8 ms − 2. Solution. Initially the food packet shares the upward velocity of the balloon, so

Electromagnets A coil with an iron core is called an electromagnet . The iron core increases the coil’s magnetic field strength. A simple electromagnet is made by coiling wire around an iron nail. A simple electromagnet Key points Iron is easily magnetised and demagnetised. Steel is more difficult to magnetise and is not easily demagnetised. An iron core makes a temporary electromagnet. It loses its magnetism as soon as the switch is opened and the current is switched off. A steel core makes a more permanent magnet. It does not lose its magnetism quickly when the current is switched off. Electromagnets with iron cores are used: • in scrap yards to lift magnetic materials such as iron and steel; • to separate magnetic materials such as iron and steel from non-magnetic materials; • in electric bells; • in relay switches and door locks that can be controlled remotely; • to hold open fire doors – the electromagnet switches off when a fire alarm is sounded and the doors close.