S-113 A proton is placed 4 cm to the right of a 1.2 nC charge and 2 cm to the left of a -2.4 nC charge. What is the acceleration of the proton? Squirrel Jedi

S-117 Four charges, each of 1.2 nC are placed on the corners of a square 2.5 cm per side. What is the magnitude and direction of the electric field on the upper right corner? What is the force on the charge in that corner?

Electric Potential AP Physics Chapter 17

Electric Charge and Electric Field 17.1 Electric Potential Energy and Potential Difference

Electric Potential Energy & Potential Difference Electricity can be viewed in terms of energy The electrostatic force is conservative because it depends on displacement Now We can calculate this value for a uniform electric field 17.1

Electric Potential Energy & Potential Difference Positive test charge – increases when moved against the field Negative test charge – increases when moved with the field Electric Potential (Potential) – electric potential energy per unit charge 17.1

Electric Potential Energy & Potential Difference Only difference in potential are meaningful Potential Difference (Electric Potential Difference) – is measureable Measured in volts (after Alessandro Volta) 17.1

Electric Potential Energy & Potential Difference If we want a specific potential value at a point, we must pick a zero point. That point is usually either A. The ground B. At an infinite distance 17.1

S-118 A 1.2 mC charge is moved 3 cm into a 231 N/C electric field. A.What is the change in potential energy? B.If the particle has a mass of 4.4 g, what will be its velocity when it has moved back 3 cm (assume all energy is converted to kinetic energy)

Electric Charge and Electric Field 17.2 Relation between Electric Potential and Electric Field

Relation between Electric Potential & Electric Field Work It also is So pew 17.2

Electric Charge and Electric Field 17.3 Equipotential Lines

Equipotential Lines Equipotential Line or Equipotential Surface – one at which all points are at the same potential 17.3

Equipotential Lines Must be perpendicular to the electric field Constant Field 17.3

Equipotential Lines Must be perpendicular to the electric field Point Charge 17.3

Equipotential Lines Must be perpendicular to the electric field Dipole 17.3

Electric Charge and Electric Field 17.4 The Electron Volt, a Unit of Energy

The Electron Volt A unit of energy – for electrons, atoms, or molecules Electron Volt (eV) 17.4

Electric Charge and Electric Field 17.5 Electric Potential Due to Point Charge

Electric Potential Due to Point Charge Using calculus it can be shown that the electric potential a distance r from a single point charge q is Assuming that potential is zero at infinity 17.5

Electric Charge and Electric Field 17.7 Capacitance

Capacitance Capacitor – device that stores electric charge In RAM, Camera Flash, 17.7

Capacitance Simple capacitors consist of two plate The symbol for a capacitor is The symbol for a cell is The symbol for a battery is 17.7

Capacitance When a potential difference is placed across a capacitor it becomes charged This process takes a short amount of time The charge on each plate is the same, but opposite charge The amount of charge is proportional to the potential difference A constant C (Capacitance) gives 17.7 Charging a Capacitor Time for RC Circuit

S-120 Two electrons are moved from an infinite distance to a location 2 cm from each other. A.What is the electric field produced by one at the location of the other? B.What is the force between them? C.What is electric potential energy due to their positions relative to each other? cat gone to dark side

Capacitance Capacitance – Unit Farad For a parallel plate capacitor, the capacitance depends on the area of the plates, the distance between the plates 17.7

Electric Charge and Electric Field 17.8 Dielectrics

Dielectrics Most capacitors have an insulator between the plates Called a Dielectric Increases the capacitance by a factor K Called the dielectric constant 17.8

Dielectrics Some Dielectric Constants 17.8 MaterialK Paper3.7 Glass5 Rubber6.7 Mica7 Strontium Titanate 300

Electric Charge and Electric Field 17.9 Storage of Electric Energy

Storage of Electric Energy A charged capacitor stores energy 17.9

S-116 A 1.7 F capacitor in a camera is charged across a 120 V socket. What is the energy stored in the capacitor?

Combinations of Capacitors

Parallel – more than one pathway For a parallel set of capacitors – the total charge is the sum of the individual charges In all parallel circuits – the potential across each branch is the same as the total Combinations of Capacitors

The equivalent capacitance is the value of one capacitor that could replace all those in the circuit with no change in charge or potential Since And We combine and get Combinations of Capacitors

Series – components of a circuit are in one pathway The magnitude of the charges is the same on each plate Combinations of Capacitors

The total potential is the sum of the potential drops across each capacitor We then use that equation and the equation for capacitance We get Combinations of Capacitors

3 10F capacitors are placed in a circuit with a 6 volt source of EMF. A.What is the equivalent capacitance, potential drop and charge if they are in series? B.What if they are in parallel? S-121

S-118 Peace Love Happiness Test

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