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Electrostatic Potential Difference

Electrostatic Potential Difference. Electrostatic Potential Difference Electrostatic Potential Electrostatic Potential for a point charge. Reading Question. What are the units of potential difference ?. 1. Amperes 2. Potentiometers 3. Farads 4. Volts 5. Henrys. Reading Question.

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Electrostatic Potential Difference

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  1. Electrostatic Potential Difference Electrostatic Potential Difference Electrostatic Potential Electrostatic Potential for a point charge

  2. Reading Question What are the units of potential difference? 1. Amperes 2. Potentiometers 3. Farads 4. Volts 5. Henrys

  3. Reading Question What are the units of potential difference? 1. Amperes 2. Potentiometers 3. Farads 4. Volts 5. Henrys

  4. Reading Question The electric potential inside a capacitor 1. is constant. 2. increases linearly from the negative to the positive plate. 3. decreases linearly from the negative to the positive plate. 4. decreases inversely with distance from the negative plate. 5. decreases inversely with the square of the distance from the negative plate.

  5. Reading Question The electric potential inside a capacitor 1. is constant. 2. increases linearly from the negative to the positive plate. 3. decreases linearly from the negative to the positive plate. 4. decreases inversely with distance from the negative plate. 5. decreases inversely with the square of the distance from the negative plate.

  6. Electric Potential Electric Potential Energy • Recall that potential energy is defined in terms of work: • F is the force acting on the object causing displacement from A to B along some path l. • The example shown is for a gravitational field but it is the same for a charged particle in an electric field. B A

  7. Electric Potential • The electric potential energy for a constant electric field is • And for a point charge

  8. Electric Potential • Now the electrical potential difference DVA->B is defined as the electrical potential energy divided by the charge. Find the electrical potential difference. • What are the units for potential? electrical potential difference J/C=V

  9. Electric Potential

  10. decreases increases does not change Electrostatic Potential Energy • Fill in the blanks below. • The potential difference _________ if a positive charge moves in the direction of the electric field and ________ if the positive charge moves in the direction opposite the electric field. The potential difference ______________ if the positive charge moves perpendicular to the electric field. • What about a negative charge? • If we know the electrical potential difference we can find the change in electrical potential energy from the definition for electrical potential difference.

  11. decreases increases does not change Electrostatic Potential Energy • Fill in the blanks using • The potential energy of a positive charge __________ if the charge move in the direction of the electric field and __________ if the positive charge moves in the opposite direction to the electric field. The potential energy of a positive charge _______________ if the charge moves perpendicular to the electric field. • How does this statement change if the charge is negative?

  12. But from a to C Electrostatic Potential Energy • Electrical Potential Difference for a Point Charge • The electrical potential difference for a point charge is • Now lets derive this! C

  13. Electrostatic Potential Energy • Electrical Potential for a Point Charge • For point charges we define the potential to be zero at infinity. Set rA equal to infinity. • This is Equation 25-4 in your text. This expression allows you it find the potential at any point in space for a point charge. where

  14. Electric Potential

  15. V(r) y x location of positive point charge Electric Potential Potential for a point charge. How would the figure change if the positive charge is replaced by a negative charge?

  16. Electric Potential Electrical Potential for a Dipole. location of positive charge location of negative charge

  17. A 5 C m 3 m -7 C 3 C m m 7 m Electric Potential • This is a scalar equation so the potential for two or more charges is just the scalar sum of the potential for each charge. This is called superposition. • Find the potential at A for the three charges shown below.

  18. A 5 C m 3 m -7 C 3 C m m 7 m Electric Potential • The way to work this problem is to find the potential at A for each charge and then add the potentials. Make sure you keep the sign of the potential. Find the electrical potential difference for the 5mC charge.

  19. First we need to find r for the -7mC charge. A Then 5 C m 3 m -7 C 3 C m m 7 m Electric Potential • Now find the electrical potential for the -7mC and 3mC charges.

  20. Electrostatic Potential Energy What is the potential for a charged ring on axis? r is the distance from the charge, dq to the point where the potential is evaluated.

  21. Student Workbook

  22. Student Workbook

  23. Student Workbook

  24. Student Workbook

  25. Student Workbook

  26. Student Workbook

  27. Student Workbook

  28. Student Workbook

  29. Student Workbook

  30. Student Workbook

  31. Student Workbook

  32. Student Workbook

  33. Reading Question The positive charge is the end view of a positively charged glass rod. A negatively charged particle moves in a circular arc around the glass rod. Is the work done on the charged particle by the rod’s electric field positive, negative or zero? 1. Positive 2. Negative 3. Zero

  34. Reading Question The positive charge is the end view of a positively charged glass rod. A negatively charged particle moves in a circular arc around the glass rod. Is the work done on the charged particle by the rod’s electric field positive, negative or zero? 1. Positive 2. Negative 3. Zero

  35. Reading Question The positive charge is the end view of a positively charged glass rod. A negatively charged particle moves in a circular arc around the glass rod. Is the change in electric potential of the charged particle positive, negative or zero? 1. Positive 2. Negative 3. Zero

  36. Reading Question The positive charge is the end view of a positively charged glass rod. A negatively charged particle moves in a circular arc around the glass rod. Is the change in electric potential of the charged particle positive, negative or zero? 1. Positive 2. Negative 3. Zero

  37. Reading Question A proton is released from rest at point B, where the potential is 0 V. Afterward, the proton 1. moves toward A with an increasing speed. 2. moves toward A with a steady speed. 3. remains at rest at B. 4. moves toward C with a steady speed. 5. moves toward C with an increasing speed.

  38. Reading Question A proton is released from rest at point B, where the potential is 0 V. Afterward, the proton 1. moves toward A with an increasing speed. 2. moves toward A with a steady speed. 3. remains at rest at B. 4. moves toward C with a steady speed. 5. moves toward C with an increasing speed.

  39. Reading Question Rank in order, from largest to smallest, the potentials Va to Ve at the points a to e. 1. Va = Vb = Vc = Vd = Ve 2. Va = Vb > Vc > Vd = Ve 3. Vd = Ve > Vc > Va = Vb 4. Vb = Vc = Ve > Va = Vd 5. Va = Vb = Vd = Ve > Vc

  40. Reading Question Rank in order, from largest to smallest, the potentials Va to Ve at the points a to e. 1. Va = Vb = Vc = Vd = Ve 2. Va = Vb > Vc > Vd = Ve 3. Vd = Ve > Vc > Va = Vb 4. Vb = Vc = Ve > Va = Vd 5. Va = Vb = Vd = Ve > Vc

  41. Reading Question Rank in order, from largest to smallest, the potential differences ∆V12, ∆V13, and ∆V23 between points 1 and 2, points 1 and 3, and points 2 and 3. 1. ∆V12 > ∆V13 = ∆V23 2. ∆V13 > ∆V12 > ∆V23 3. ∆V13 > ∆V23 > ∆V12 4. ∆V13 = ∆V23 > ∆V12 5. ∆V23 > ∆V12 > ∆V13

  42. Reading Question Rank in order, from largest to smallest, the potential differences ∆V12, ∆V13, and ∆V23 between points 1 and 2, points 1 and 3, and points 2 and 3. 1. ∆V12 > ∆V13 = ∆V23 2. ∆V13 > ∆V12 > ∆V23 3. ∆V13 > ∆V23 > ∆V12 4. ∆V13 = ∆V23 > ∆V12 5. ∆V23 > ∆V12 > ∆V13

  43. Electrostatic Potential Energy • EEG

  44. Electrostatic Potential Energy • EEG

  45. Electric Potential • EKG

  46. Electrostatic Potential Energy • EKG

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