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Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
Electromagnetism
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Electromagnetism

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A set of slides created to teach Electromagnetism to learners at Bishops Diocesan College in Cape Town.

A set of slides created to teach Electromagnetism to learners at Bishops Diocesan College in Cape Town.

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  • 1. Electromagnetism K Warne
  • 2. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Magnetic Effect A magnetic field is generated around any conductor when an electric current flows through it. Electric current Wire with current coming towards you Wire with current going away from you x
  • 3. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net SOLENOID A coil generates a very concentrated (strong) magnetic field in its center. Electric current x N S x x Increasing the number of coils strengthens the magnetic field. The Right Hand Rule can also be applied to a solenoid! INSIDE THE COIL THE FIELD GOES FROM SOUTH TO NORTH!!!
  • 4. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Solenoid Field • Note field same as bar magnet • Inside S  N!!!!!  Web Applet Demo>>
  • 5. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Electromagnetic Induction N S ........An electrical conductor that is accelerated through a magnetic field will experience an INDUCED electrical current according to Fleming's Right Hand Rule. Thrust ................ ............ ................ Forefinger Second Thumb Faraday’s Law The size of the induced current is directly proportional to the rate of change of the magnetic flux linkage. Current??
  • 6. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Induction examples N S In each example the movement of the conductor is given by the red arrow. State or show which way will the current be generated? N S S N N S 1. 2. 3. 4. N S S N 5. 6. 7. 8. S
  • 7. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Electric Field Strength • Total number of field lines is called ………………….. (…….) measured in ………………. (……)  = ………. •  = ………………….. (………) • B = ……………………. (……) • A = ………………. through which flux passes N S +- Magnetic field Strength (B) measured in ……………… (………) Thrust 1 ………….. is the field ……………. when a current of …….. A flows through a conductor and it experiences a ………….. of …N per meter of length. (… ….) (…..) (…...) = no of ………. in that area.
  • 8. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Electric Field Examples • Calculate the magnetic field strength if magnetic flux of 0.5 Wb is established over an area of 10 cm2 . • What magnetic flux would be needed if a 1Tesla magnetic field is needed across a 0.5m2 area? • What area would be covered by a 100T magnetic field if the magnetic flux density was 20 Wb? ANSWERS >>
  • 9. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Faraday’s Law The induced emf (….) is directly proportional to the …………. of change of ………………….. The size of the induced ……………… is (also) directly proportional to the ………………………. of the ……………………………………...   N  t S N The induced emf can be increased by: • Increasing the ………………… • Using ……………………… • Decreasing the …………. – moving ………..
  • 10. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Lenz’s Law • The induced field …….. (………………) is induced in such a way as to ……………… the ……… causing it.
  • 11. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Mutual Induction • MUTUAL INDUCTION is defined as the changing electric …………………… producing a changing …………………….. field which can produce a changing ………………….. in another conductor. • This is the basic principle of the ……………………… ~
  • 12. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Transformers• Ideally – all magnetic flux from primary coil links with secondary coil. • The number of turns of wire is directly proportional to the voltage in the coil. Np Vp Ns Vs — = — How many turns of wire would you need in a transformer that has 1000 turns in the primary and needs to step down the voltage from 220V to 9V? ........... Voltage A. C in. ............. Voltage A. C OUT. STEP ................TRANSFORMER .......... turns .......... turns Vp = Vs Np Ns
  • 13. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Transformers From Faraday’s Law: “The size of the induced current is directly proportional to the rate of change of the magnetic flux linkage.” • Therefore: work done by primary = energy gained by secondary Since W = QV and Q = It .: W = VIt Wp = Ws ......... = ........... ........... = ............. ......... = ........... Calculate the current in the secondary coil of the 220V/9V transformer if the current in the primary was 1.5A
  • 14. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Hi - This is a SAMPLE presentation only. My FULL presentations, which contain a lot more more slides and other resources, are freely available on my resource sharing website: www.warnescience.net (click on link or logo) Have a look and enjoy! WarneScience

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