632 PM Week 6 Session 1 DOCX 58 KB 00 Ooredoo Close Task 1 A

6:32 PM Week 6 Session 1 DOCX 58 KB 00 Ooredoo Close Task 1. A. Read the text and answer the questions. Transformers are so required for the operation of most luminous discharge tubes and for bell system in the home; they are found in radio and television equipment, with several different types often used in the same circuit; telephone system use large numbers of transformers as does X-ray equipment: so that we might say that where electricity is used, transformers are used too. Essentially a transformer consists of two independent electric circuits linked with a common magnetic circuit. In particular, it usually consists of two coils or windings of insulated iron core. An alternating magnetic flux is produced in this iron core when an alternating current passes through the insulated conductors. In operation, an A.C. supply is connected to one winding which thereby becomes the primary winding: the other winding, to which the load is connected, is called the secondary winding. The magnetic flux in the magnetic circuit formed by the iron core links the turns of the primary and the secondary windings. If this flux is the same for each of the two windings, the induced emf in each winding will be proportional to the number of turns on that winding. The transformer is based on two principles: first, that an electric current can produce a magnetic field (electromagnetism) and second that a changing magnetic field within a coil of wire induces a voltage across the ends o the coil (electromagnetic induction). Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil. copper wire around a laminated . What do you think the word luminous means? 2. How is electromagnetic field produced? Explain it briefly Email Word CP save Word Save 3. What is the relationship between a copper wire and laminated iron core?

Solution

1) Bright
2) Moving charge produces electromanginetic field. When a charge moves it produces electric field and when velocity of charge changes it produces magnetic field. Oscillating current like AC produces electromagnetic fields
3) Copper wire is a good conductor of current and laminated iron core has very high permeability which produces high magnetic flux. Copper wire is winded on iron core so that when current passes through copper wire high magnetic flux is produced by iron core

1) False, 2 electric circuits with a common magnetic circuit
2) Ture
3) False, it is propotional
4) Ture
5) True

1) The report was written by Ali Al Habsi
2) The generator was driven by a petrol engine
3) The copper conductors were held by insulating wedges in the slots
4) The switching was carried out by an automatic circuit breaker

1) Better reliability can be obtained by means of transistorized circuits
2) A magneto motive force was obtained by means of field coils to establish the flux in the magnetic circuit

1) principles, magnetic, electromagnetism, field, induces, induction, changing, primary, flux, developed, voltage, secondary

1) higher, lower
2) simpler, easier
3) simplest
4) cheaper, more useful
5) most important
6) most common
7) more popular

1) A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction
2) Hysteresis loss is due to reversal of magnetization in the transformer core. In transformer, AC current is supplied to the primary winding which sets up alternating magnetizing flux
3) For DC current impedance acts just like resistance
4) It is constant
5) Current will keep running in primary circuit, but no current in secondary circuit