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Frogs' Legs, Peas and Potatoes: Electricity in Action

Frogs' Legs, Peas and Potatoes: Electricity in Action. Elisa De Ranieri University of Cambridge. 1 st VC, 06 Feb 2007. What we are going to do today. introduction to electricity: where do we find it? . 2. electric current going in circuits. 3. can a potato be transformed in a battery?.

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Frogs' Legs, Peas and Potatoes: Electricity in Action

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  1. Frogs' Legs, Peas and Potatoes: Electricity in Action Elisa De Ranieri University of Cambridge 1st VC, 06 Feb 2007

  2. What we are going to do today • introduction to electricity: where do we find it? 2. electric current going in circuits 3. can a potato be transformed in a battery?

  3. LATTICE Atoms in a crystal What is electricity? Presence and motion of charged particles Electricity Electric current is the flow of charged particles through a close path as an electric circuit.

  4. Free to move Bound to atoms CONDUCTOR INSULATOR What is electricity? Presence and motion of charged particles Electricity Electric current is the flow of charged particles through a close path as an electric circuit. Electrons in the lattice

  5. What is electricity?

  6. Electricity is everywhere… Where do we find electricity?

  7. Electricity is everywhere… Christmas lights

  8. Electricity is everywhere… Cars

  9. Electricity is everywhere… Electronic devices

  10. Electricity is everywhere… Human body

  11. Understanding electricity Understanding electricity is important in your studies and everyday life! My device fabricated on a semiconductor Modelled with a series of 3 resistors = 50 m

  12. ELECTRIC CIRCUITS

  13. R - + OHM’S LAW I V V = R * I Symbols and Ohm’s law bulb resistor cell switch + V -

  14. PARALLEL SERIES Electrical connections If a Christmas light blows, what happens to the other ones? They don’t blow because Christmas lights are connected IN PARALLEL

  15. + + + - - - V3 V1 V2 I I I I Series + - V I1 = I2 = I3 = I V1 + V2 + V3 = V

  16. I Parallel I1 I2 I3 + + + + V - V V V - - - I I1 + I2 + I3 = I V1 = V2 =V3 = V

  17. Brightness I = V / R

  18. Brightness I I = V / R 0.3 I less bright less current

  19. Brightness I = V / R

  20. Brightness I I = V / R 3 I I Same brightnesssame current

  21. I What if we introduce a switch Sa + I V -

  22. What if we introduce a switch I = 0 Sa + I = 0 V - I = 0

  23. I What if we introduce a switch I2 + Sb V - I1

  24. I What if we introduce a switch I2 = I + Sb V - I1 = 0

  25. What if we introduce 2 switches I = 0 1 Sa I2 = 0 + Sb V - 2 3 I1 = 0

  26. What if we introduce 2 switches I = 0 Sa I2 = 0 + Sb V - I1 = 0

  27. I What if we introduce 2 switches Sa I2 = I + Sb V - I1 = 0

  28. I What if we introduce 2 switches Sa I2 + Sb V - I1

  29. Predict the action of the switches 2 1 Sa + Sb 4 V - 3 Sd Sc 5

  30. HOME-MADE CELL

  31. How cells work Electrodes (uncharged) made with different metals Electrolyte: ionic solution

  32. How cells work electrode negatively charged positive ions that pass into solution

  33. Electrons Ions How cells work I 0 A

  34. The potato-cell bulb I ??? iron wire nail potato

  35. What we have learnt • Electricity is everywhere around us! • The basic concepts related to electricity (V, I, R) • To predict the effect of switches in a circuit with series and parallel connections • To turn a potato into a battery

  36. Project work • Making connections • Sources of electricity • Research on pioneers of electricity!

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