ch. 19 - electric potential and electric energy

electric energy

energy carried by flow of charge

conservative force

a force that does the same work for any given intial and final configuration, regardless of the path followed

W= -deltaPE

work done by a conservative force (like electrostatic force) formula

V = PE/q

electric potential formula

potential difference

(delta V) difference in electric potential between two points in an electric circuit; work needed to move a unit charge from one point to another

1J/C

1V

deltaPE = deltaV(q)

relationship between change in potential energy, test charge, and potential difference

electric potential

amount of electric potential energy (PE) per unit charge (q)

• SCALAR

volt

SI unit for electric potential

electron volt

energy given to a fundamental charge acceralated through potential difference of 1V

conservation of energy of conservative forces

mechanical energy is constant

PE + KE = constant

KE(i) + PE(i) = KE(f) + PE(f)

E(d)=deltaV

relationship between potential difference and electric field

V/M

N/C (electric field units)

points in the direction of decreasing potential

electric field…

V=k(Q)/r

electric potential due to point charge formula

equipotential lines

lines where the electric potential is constant (deltaV=0)

perpendicular to electric field lines

equipotenital lines are…

grounding

conductor can be fixed at 0 volts by connecting it to Earth with a good conductor

capacitor

device used to electric charge

parallel plate capacitor

system composed of two identical parallel conducting plates separated by distance

the greater the charge stored it in.

the greater the voltage applied to any capacitor…

capacitance

amount of charge stored per volt (Q/V)

C = Q/V

capacitance formula

farad

SI unit for capacitance (F)

Large A

small d

factors that increase capacitance in parallel plate capacitor

C = e(0)A/d

the capacitance of a parallel plate capacitor in equation form is given by:

e(0)

constant; permitivity of free space

8.85 × 10^-12

=e(0) (units F/m)

dielectric

insulating material

C = ke(0)A/d

capacitance of a parallel plate capacitor with a dielectric between its plate

k

dielectric constant; value varies

dielectric strength

maximum electric field strengths above which the material begins to break down and conduct

the greater the k

the more a dielectric is able to polarize…

k=E0/E

dielectric constant is defined by the ratio of electric field of vacuum to that dielectric material

series

a sequence of resistors or other components wired into a circuit one after the other

• the capacitance is less than any of the individual capacitances

parallel

the wiring of resistors or other components in an electrical circuit such that each component receives an equal voltage from the power source

1/C1 + 1/C2 + 1/C3… = 1/C total

equation for the total capacitance in a series

C1 + C2 + C3…=C total

equation of total capacitance in parallel

electrical potential energy

energy stored in capacitors

E = QV/2

energy stored in a capacitor equation