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Aim: How can we explain Electric Potential?

Aim: How can we explain Electric Potential?. Do Now: What is the change in gravitational potential energy if you move a 25 kg object from 3m above the ground to 5m above the ground?. Gravitational Potential Energy. Δ PE = mg Δ h Δ PE = (25kg)(9.8m/s 2 )(2m) Δ PE = 490 J

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Aim: How can we explain Electric Potential?

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  1. Aim: How can we explain Electric Potential? Do Now: What is the change in gravitational potential energy if you move a 25 kg object from 3m above the ground to 5m above the ground?

  2. Gravitational Potential Energy • ΔPE = mgΔh • ΔPE = (25kg)(9.8m/s2)(2m) • ΔPE = 490 J • In order to move from the initial height to final height, what needed to be done on the object? Work

  3. How does this relate to electric charges? • Volunteers?

  4. Electric Potential • The work required to move a positive test charge in an electric field • Pt A has higher electric potential than B b/c it takes more work to move a positive test charge to A than B A B

  5. Potential Difference or Potential Drop • The change in energy per charge, as the charge moves from one point to another • W = Work (Joules) • q = Charge (Coulombs) • V = Potential Difference • Units: = Volt

  6. Alessandro Volta 1745-1827

  7. What is the potential difference between 2 pts if it takes 10 J of work to move +2 C of charge from A to B? V = W q V = 10 J 2 C V = 5 volts

  8. How much work is required to move an elementary charge through a potential difference of 3 volts? V = W q 3 volts = W 1.6 x 10-19 C W = 4.8 x 10-19 Joules

  9. Electronvolt (eV) • The work required to move 1 elementary charge through a potential difference of 1 volt • 1 eV = 1 volt x 1 elementary charge = 1.6 x 10-19 J

  10. How much work does it take to move 2 protons through a potential difference of 5 volts (answer in eV)? V = W q 5 volts = W 2e W = 10 eV Convert to Joules = 1.6 x 10-18 J

  11. Final example: • How much work is required to move an 8 x 10-16 C of charge through a potential difference of 8 volts? (express answer in eV) A) 6.4 x 10-15 eV B) 4.0 x 104 eV C) 1.0 x 10-33 eV D) 6.3 x 10-53 eV

  12. Parallel Plate Formula • V = Electric potential (volts) • d = Distance between plates (meters) • E = Electric field Units: Remember: Units of E are as learned from the previous lesson Therefore, =

  13. If d = 2 x 10-3 m and V = 4 x 103 V, (a) find E

  14. (b) How much work does it take to move 10 electrons across the plates in (1) eV and (2) Joules V = W/q 4 x 103 V = W 10e W = 4 x 104 eV = 6.4 x 10-15 J

  15. If d =3.5 x 10-2 m and V = 3.2 x 104 V, (a) find E

  16. (b) How much work does it take to move 4 electrons across the plates in (1) eV and (2) Joules V = W/q 3.2 x 104 V = W 4e W = 1.3 x 105 eV = 2.08 x 10-14 J

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