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ELECTRICITY

ELECTRICITY. Electric Charge Electric Force Electric Field. Electric Charge. An excess or shortage of electrons produces a net electric charge. The force of attraction or repulsion between electrically charged objects is Electric Force. ELECTRIC FORCE DEPENDS ON CHARGE AND DISTANCE.

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ELECTRICITY

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  1. ELECTRICITY Electric Charge Electric Force Electric Field

  2. Electric Charge • An excess or shortage of electrons produces a net electric charge

  3. The force of attraction or repulsion between electrically charged objects is Electric Force

  4. ELECTRIC FORCE DEPENDS ON CHARGE AND DISTANCE • The electric force between 2 objects is directly proportional to the net charge • Inversely proportional to the square of the distance

  5. ELECTRIC FIELDS • The effect an electric charge has on other charges in the space around it is the charge’s electric field • The strength of an electric field depends on the amount of charge that produces the field and on the distance from the charge

  6. STATIC ELECTRICITY • Friction • Contact • Induction • Discharge

  7. STATIC ELECTRICITY • the build up of a net charge on an object • Charge can be transferred by friction, by contact and by induction • Thecharge is NOT moving along a wire or conductor

  8. FRICTION • You can also run a comb through your hair to charge the comb with static electricity. The comb can then be used to attract neutral pieces of tissue.

  9. Charging by Contact

  10. Charging by induction • 1) A negatively charged rod is brought towards a neutral conductor. • 2) Negative charges are repelled from this rod. • 3) If the conductor is then earthed, these negative charges can get even further – they flow to earth. • 4) The conductor is no longer earthed, and the rod is taken away. The conductor is left with a positive charge.

  11. STATIC Discharge • Occurs when a pathway through which charges can move forms suddenly

  12. ELECTRIC CURRENT and OHM’S LAW • Electric current • Direct current • Alternating current • Conductor • Insulator • Resistance • Superconductor • Potential difference • Voltage • Battery • Ohm’s law

  13. Electric Current: The continuous flow of electric charge • Current is measured in Ampere's or Amps • Direct Current(DC): charge flows in only one direction, like in a flashlight • Alternating current(AC): flow of electric charge that regularly reverses direction; current in your home

  14. Conductors • Electrical conductors aare materials through which charge can easily flow • Metals such as Copper and Silver are very good conductors

  15. Insulators • A material through which chaarge can not flow easily • Coaating around a wire is an example of an insulator—it controls the current • Wood, plastic, rubber and air aare good electrical insulators

  16. Resistence • Opposition to the flow of charges in a material • SI unit is the OHM

  17. What affects resistance? • Thickness of wire ( thin wires High resistance) • Length of wire(long wires, greater resistance) • Temperature(increased temperature causes electrons to collide more frequently)

  18. SUPERCONDUCTOR • A material that has almost zero resistance when it is cooled to low temperatures

  19. VOLTAGE • Voltage is the Potential Difference in electriccal potential between two places in an electric field • Measured in Volts • Charges flow spontaneously from a higher to a lower potential

  20. Voltage sources • Battery • Solar cells • Generators

  21. Battery • Converts chemical energy to electrical energy • Have one positive and one negative terminal • Voltage drop or potential difference is maintained across the terminals

  22. Parts of a Battery

  23. DRY CELL

  24. Ohm’s Law • Voltage (V) in a circuit equals product of current(I) and Resistance(R) • V = I x R or

  25. Ohm’s Law • What is the voltage if the current is 3 amps and the resistance is 3 ohm’s? • V = I x R • V = 3 amps x 3 ohms • V= 9 volts • Increasing the voltage, increases the current • Keeping same voltage and increasing resistance, decreases current

  26. Circuits • Electric circuit is a complete path through which charge can flow • Circuit diagrams use symbols to represent parts such as battery, resistor or light

  27. Types of Circuits • Series: • Charge has only one path through which it can flow; adding bulbs will diminish the brightness of the bulbs • Parallel: • Circuit with 2 or more paths through which charges can flow; most circuits in a house are parallel circuits

  28. SERIES CIRCUIT

  29. ParallelCircuit

  30. Electric Power • The rate at which electrical energy is converted to another form of energy is electric power • Calculated by multiplying voltage by current • P (watts) = I (amps) X V (voltage)

  31. Electrical Safety

  32. Electrical Safety • Correct wiring , fuses, circuit breakers, insulation and grounded plugs help make electrical energy safe to use • Fuse: prevents current overloaad in a circuit • Circuit breaker: opens when current in circuit is too high , must be reset before circuit can be used again • Grounding: the transfer of excess charge through a conductor to the Earth

  33. Formation of Lightning

  34. Solenoid

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