Basic Electrical Installation Work

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5. . Definition Like poles repel; unlike poles attract. 8. The places magnetic material where the lines flux are con- centrated are called the magnetic poles. The symbol used for flux density and the unit flux density the tesla (symbol T), commemorate the work the Croatian-born American physicist Nikola Tesla (1857–1943). The magnetic fields around a permanent magnet are shown Figs 5. The number lines magnetic flux within magnetic field a measure the flux density. The region space through which the influence magnet can be detected called the magnetic field that magnet. 4. Strong magnetic fields have high-flux density. Like poles repel; unlike poles attract. 5. Lines magnetic flux pass through space and non-magnetic materials undisturbed.13 and 5. These two statements are sometimes called the ‘first laws magnetism’ and are shown in Fig. 9.Basic scientific concepts electrotechnology 113 3. Gently tapping the paper then causes the filings take the shape the mag- netic field surrounding the permanent magnet. Definition The places magnetic material where the lines flux are concen- trated are called the magnetic poles. 10. Bar magnet Horse shoe magnet N S N S FIGURE 5. Lines magnetic flux travel along magnetic material and always emerge out the ‘north pole’ end the magnet. Magnetic fields If permanent magnet placed surface and covered piece of paper, iron filings can shaken the paper from dispenser.13 Magnetic fields around permanent magnet. These two statements are sometimes called the‘first laws magnetism’and are shown Fig. 7. 6. Lines magnetic flux never cross over each other.14.14.14. Definition The region space through which the influence magnet can be detected called the magnetic field of that magnet. Lines magnetic flux behave like stretched elastic bands, always trying shorten themselves. 5