electric field, potential and energy
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Electric field, potential and energy. Topic 9.3 (AHL). Remember?. Define potential difference (voltage). Remember?. Define potential difference (voltage). Amount of electrical energy converted to heat when a charge flows through a resistor. EPE. Draw the electric field lines. EPE. - PowerPoint PPT PresentationTRANSCRIPT
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Electric field, potential and energy
Topic 9.3 (AHL)
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Remember?• Define potential difference (voltage).
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Remember?• Define potential difference (voltage).
• Amount of electrical energy converted to heat when a charge flows through a resistor.
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EPE• Draw the electric field lines.
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EPE• If a positive charge was placed in the plate.
Which direction will it move?
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EPE• Which direction will require you to do some
work?• When you do this work will it increase its KE
or PE?
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EPE• What’s the direction of the electric force on
positive charge? State equation
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EPE• F= Eq, then to move the positive charge from
negative to positive plate, we need to apply equal and opposite force.
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EPE• Therefore the work done = Fd = Eqd = Eqh• We increased the electrical PE (EPE)
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Electric potential• Where will you have the greatest electrical
potential energy?• Can you define electric potential at a point?
(remember gravitational potential and change the terms)
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Electric potential• Where will you have the greatest electrical
potential energy?• Can you define electric potential at a point?
Work done per unit charge taking a small positive test charge from infinity to a point.
• Unit?
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Electric potential• Where will you have the greatest electrical
potential energy?• Can you define electric potential at a point?
Work done per unit charge taking a small positive test charge from infinity to a point.
• Unit? JC-1 or Volts• Potential is a scalar quantity• Reminder: at infinity you have zero potential
(like gravitational)
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Electric potential• Where will you have zero potential?• Greatest potential?• Equal potential (equipotential)
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Electric potential• Where will you have zero potential? bottom• Greatest potential? Top • Equal potential (equipotential)
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Electric potential• Equation for change in potential?
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Electric potential• Equation for change in potential?
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Electric potential• Draw field lines and equipotential lines for the
a positive test charge.
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Electric potential• Draw field lines and equipotential lines for the a
positive test charge.(red: equipotential line, black: field lines)
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Electric potential• Draw field lines and equipotential lines when two
positive charges are brought close to each other.
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Electric potential• Draw field lines and equipotential lines when two
positive charges are brought close to each other.• Try other patterns on simulation.
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Force VS distance graph
• Force more or less if two positive charges get closer to each other? Predict shape of graph
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Force VS distance graph
• Force more or less if two positive charges get closer to each other? Predict shape of graph
gravitational
electrical
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Force VS distance graph
• What will the area represent? Equation
electrical
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Force VS distance graph
• What will the area represent? Equation
electrical
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Potential vs distance• How will the graph look like for a positive
charge?
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Potential vs distance• Potential inside positive sphere is constant• What will the tangent represent?
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Potential vs distance• What will the tangent represent?
• -E (since E will be positive)
x
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E and V graphs
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E and V graphs
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Wells and hills• In gravitational we saw the wells
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Wells and hills• In electrical it can be both wells and hills.
• Well is potential is decreasing as you approach ? charge
• Hill if potential increasing as you approach ? charge
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Wells and hills• In electrical it can be both wells and hills.
• Well is potential is decreasing as you approach negative charge
• Hill if potential increasing as you approach positive charge
A combination of positive and negative charge is called a dipole
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Addition of potential• Potential is scalar therefore add without
considering direction
+ –
P
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Questions 30,31 P.203• Which charge is positive which is negative and explain
• If a positive charge is placed at A, would it move? In which direction if yes
• In which point is the field strength greatest?
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Questions 30,31 P.203
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comparison