AP Physics 2 Semester 1 Final Exam Review

AP Physics 2

Current

rate of flow of electric charge through a cross-sectional area (I)

Current Equation I =

Q/t

Current Unit

Amps / Amperes (A)

Current Conversion Rate

1 A = 1 C/s

Current Direction

Current flows towards positive charge

What causes I

Force of E

Drift Velocity

Average movement of electrons in circuit. Opposite of force E and opposite of current

n

Number density of charge carriers

Q/t = qnAv

Current

I = qnAvt

Relationship between current and drift velocity

What direction does force E point

decreasing potential

Resistance

Ratio of potential drop to the current

Resistance Equation

V/I

Resistance Conversion: 1 ohm =

1 V/A

Ohm’s Law

I is directly proportional to V and inversely proportional to R

Ohm’s Law Equation

V = IR (R constant)

Ohmic graphs are

linear

Nonohmic graphs are

non linear

Wire Resistance Equation

R = p x L/A

Resistance in a wire is proportional to

length

Resistance in a wire is inversely proportional to

cross-sectional area

p

resistivity of conducting material

What unit is wire resistivity measured in

Ohm-meters

Resistivity is largely dependent on

T

Rate of Energy Loss Equation

-U/-t = Q/t x V = IV

P = VI

energy loss per unit of time is power dissipated from conducting segment

P Units

Watts

Power Dissipated in a Resistor (Equation)

P = V² / R

Electromotive Force

provided by battery to generate electric field

What does the emf source do to a charge

work is done, raising potential energy

Work per unit of charge

emf

EMF Units

Volts

Resistors in Series

carry the same current

Resistors in Series Equation

R(eq) = R(1) + R(1) + R(1) + …

Parallel Resistors

have the same potential difference across them

Parallel Resistors Equation

R(eq) = 1/R(1) + 1/R(1) + 1/R(1) + …

Kirchhoff's Rules

Loop and Junction

Loop Rule

Net change in potential must be zero

Junction Rule

If I1 splits into I2 and I3 then I2 + I3 must equal I1

RC Circuit

contains a resistor and a capacitor

Ohm’s Law

I is directly proportional to V and inversely proportional to R

Capacitance Equation

C = Q/V

Unit of Capacitance

Farad

Permittivity of Free Space ( e0)

8.85 × 10^-12 F/m = 8.85 pF/m

Micro Farad

1 uF = 10^-6 F

Pico Farad

1 pF = 10 ^-12 F

Permittivity of Free Space Unit

Farad per meter

Capacitance Equation for Sphereical Capacitors

C = 4(pie)(e0)R

What does not matter for capacitance

charge

Potential Difference Equation (V)

= E x d

Capacitance Equation

= Q / V = (e0)A / d

Capacitance is proportional to

area of plates

Capacitance is inversely proportional to

plate seperation distance

Q in a capacitor will equilibrate when

its potential difference is equal to the potential energy of the battery terminals

U

total energy stored in a capacitor

Energy Stored in a Capacitor Equation

½ x QV = ½ X CV²

Columb’s Law

the force exerted by one point charge on another acts along the line between charges. It varies inversely as the square of the distance separating the charges and is proportional to the product of the charges. The force is repulsive if the charges have the same sign and attractive if the charges have opposite signs.

Magnitude of Electric Force Equation

F = k |(q1)(q2)| / r²

Coulomb Constant

k = 8.99 × 10^9 N x m² / C²

Law of Conservation of Charge

Charge is conserved and cannot be created or destroyed

Coulomb

amount of charge that flows through a wire in one second when I = 1 ampere

Fundamental Unit of Charge / Charge of One Electron

e = 1.602 × 10^-19 C

Electric Field Equation

E = F / (q0)