AP Physics C: Electricity and Magnetism Ultimate Guide

Charge

It is a fundamental property of matter that describes the amount of electrical energy present in an object.

Coulomb

SI unit of charge

Electric charge

It is a fundamental property of matter that arises from the presence or absence of electrons in an atom.

Conductors

These are materials that allow electric charge to flow freely through them.

Insulators

These are materials that do not allow electric charge to flow easily.

law of electrostatics

a set of fundamental principles that govern the behavior of electric charges at rest.

Coulomb's law

This law states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Electric field

A region in space where an electric charge experiences a force.

Electric potential difference

It is the difference in electric potential between two points in an electric field. It is measured in volts (V).

Charging

It is the process of adding electrical energy to a system.

Discharging

It is the process of releasing electrical energy from a system.

Electrostatic force

It is the force that exists between electrically charged particles.

Electrostatic Force Formula

Electric field strength

It is the force per unit charge experienced by a test charge placed in an electric field. It is a vector quantity and is denoted by E.

Capacitors

devices that store electric charge and energy.

Electric motors

devices that convert electrical energy into mechanical energy.

Particle accelerators

devices that use electric fields to accelerate charged particles to high speeds.

Electrostatic precipitators

devices that use electric fields to remove pollutants from the air.

Electric potential energy

It is the energy that a charged particle possesses due to its position in an electric field. It is defined as the amount of work required to move a charged particle from infinity to a point in the electric field.

Joule

SI unit of electric potential energy

Potential difference

It is the difference in electric potential energy per unit charge between two points in an electric circuit.

Gauss' Law

It is a fundamental principle in electromagnetism that relates the electric flux through a closed surface to the charge enclosed within that surface. It is named after the German mathematician and physicist Carl Friedrich Gauss.

Flux

It is the amount of a physical quantity passing through a given surface.

Extended charge distributions

This refer to the distribution of electric charge over a three-dimensional object.

Continuous Charge Distributions

These charge distributions are those where the charge is distributed continuously over a volume or surface.

Spherical Charge Distributions

These charge distributions are those where the charge is distributed uniformly over the surface of a sphere.

Cylindrical Charge Distributions

These charge distributions are those where the charge is distributed uniformly over the surface of a cylinder.

Planar Charge Distributions

These charge distributions are those where the charge is distributed uniformly over a flat surface.

Gauss law in Line of Charge

Gauss law in Point, Hoop, or Sphere (fully enclosed)

Gauss law in Sphere (not fully enclosed)

Gauss law in Insulating Sheet of Charge

Electric field

It is a vector quantity that describes the force experienced by a charged particle in an electric field.

zero

The electric field inside a conductor is _____, and any excess charge resides on the surface of the conductor.

surface of a conductor

The electric field on the ______ is perpendicular to the surface and is proportional to the surface charge density.

outside the surface

The electric field just ______ of a conductor is perpendicular to the surface and is equal to the electric field inside the conductor.

inside the surface

The electric field just _____ of a conductor is perpendicular to the surface and is equal to the electric field outside the conductor.

curved

The electric field on the surface of a conductor is strongest where the surface is most ____, and weakest where the surface is most flat.

Electric shielding

It is the process of reducing the electric field in a space by surrounding it with a conductive material.

Faraday cage

It is a type of electric shielding that completely surrounds a space with a conductive material, creating a barrier that prevents electromagnetic waves from entering or leaving the space.

Capacitor

An electronic component that stores electrical energy in an electric field. It consists of two conductive plates separated by a dielectric material.

Capacitance

It is the ability of a capacitor to store charge.

Parallel plate capacitor

It is a device that stores electrical energy in an electric field between two parallel conducting plates. It consists of two parallel plates separated by a dielectric material.

= εA/d

capacitance of a parallel plate capacitor

E = V/d

electric field between the plates of a parallel plate capacitor

U = (1/2)CV^2

energy stored in a parallel plate capacitor

Ceramic capacitors

These are the most commonly used type of capacitor.

Electrolytic capacitors

These are polarized capacitors that use an electrolyte as the dielectric.

Film capacitors

These are non-polarized capacitors that use a thin plastic film as the dielectric.

Tantalum capacitors

These are polarized capacitors that use tantalum metal as the anode.

Variable capacitors

These are capacitors whose capacitance can be adjusted.

E = 1/2 * C * V^2

energy stored in a capacitor

Dielectrics

These are materials that do not conduct electricity easily.

Polar dielectrics

These have a permanent dipole moment due to the presence of polar molecules.

Non-polar dielectrics

They do not have a permanent dipole moment. They are made up of non-polar molecules and do not align themselves in an electric field.

Dielectric strength

It is the maximum electric field that a dielectric material can withstand before it breaks down and conducts electricity. It is measured in volts per meter (V/m).

Voltage

It is the difference in electric potential between two points in a circuit. It is measured in volts (V) and is represented by the symbol "V".

Current

It is the flow of electric charge through a circuit. It is measured in amperes (A) and is represented by the symbol "I". It is the rate at which charge flows through a circuit.

Resistance

It is the opposition to the flow of electric current in a circuit. It is measured in ohms (Ω) and is represented by the symbol "R". It is determined by the material and dimensions of the conductor.

Power

It is the rate at which energy is transferred in a circuit. It is measured in watts (W) and is represented by the symbol "P". Power is calculated by multiplying voltage and current.

Frequency

It is the number of cycles per second in an alternating current (AC) circuit. It is measured in hertz (Hz) and is represented by the symbol "f". It determines the speed at which the AC signal alternates.

Impedance

It is the total opposition to the flow of electric current in a circuit. It is measured in ohms (Ω) and is represented by the symbol "Z". It is a combination of resistance, capacitance, and inductance.

Current

It is the flow of electric charge through a conductor.

Direct current (DC)

Current flows in one direction only.

Alternating current (AC)

Current changes direction periodically.

Ohm's Law

It states that the current through a conductor between two points is directly proportional to the voltage across the two points, and inversely proportional to the resistance between them.

V = I * R

Ohm's Law Formula

Resistance

it is the opposition that a material or a circuit offers to the flow of electric current.

Fixed resistors

These have a fixed resistance value and cannot be changed.

Variable resistors

These have a variable resistance value and can be adjusted.

Thermistors

These have a resistance that varies with temperature.

Light-dependent resistors

These have a resistance that varies with light intensity.

Circuit measuring tools

These are used to measure various electrical parameters in a circuit.

Multimeter

A versatile tool that can measure voltage, current, and resistance. It is used to troubleshoot circuits and check the continuity of wires and components. They come in both analog and digital versions.

Oscilloscope

Used to measure and display voltage signals over time. It is used to analyze waveforms and diagnose problems in circuits. They come in both analog and digital versions.

Function generator

Used to generate various types of waveforms such as sine, square, and triangle waves. It is used to test circuits and simulate different types of signals.

Logic analyzer

Used to capture and analyze digital signals in a circuit. It is used to troubleshoot digital circuits and analyze the behavior of digital signals.

Power supply

Used to provide a constant voltage or current to a circuit. It is used to test circuits and power electronic devices.

LCR meter

Used to measure the inductance, capacitance, and resistance of a circuit. It is used to test and design circuits that use inductors, capacitors, and resistors.

Series circuit

It is a circuit in which the components are connected in a single loop, so the current flows through each component in turn.

Parallel circuit

It is a circuit in which the components are connected in separate branches, so the current divides between them.

Electrical circuits

These are often used to convert electrical energy into other types of energy.

Kirchhoff's Voltage Law (KVL)

It is a fundamental law in electrical engineering that states that the sum of all voltages around a closed loop in a circuit must be zero. This law is based on the principle of conservation of energy, which states that energy cannot be created or destroyed, only transferred from one form to another.

Kirchhoff's Current Law (KCL)

it is a fundamental law in electrical engineering that states that the total current entering a node or junction in a circuit must be equal to the total current leaving that node or junction.

Electromotive forces

the voltage generated by a battery or other source of electrical energy.

1/C_total = 1/C_1 + 1/C_2 + ... + 1/C_n

Capacitors in Series Formula

C_total = C_1 + C_2 + ... + C_n

Capacitors in Parallel Formula

RC circuits

These are circuits that contain a resistor and a capacitor. These circuits are used in a variety of applications, including filters, timing circuits, and oscillators.

Magnetic fields

These are created by moving electric charges.

force from a magnetic field

F = q(v x B)

Lorentz force (When a charged particle moves through a magnetic field, it experiences a force perpendicular to both the direction of motion and the magnetic field. )

F = qE

When both magnetic and electric fields are present, the particle experiences a combined force that is the vector sum of the two individual forces.

F = I L x B

When a wire carrying current is placed in an external magnetic field, it experiences a force.

B_perp = B sin(theta)

If the wire is not perpendicular to the magnetic field, then only the component of the magnetic field perpendicular to the wire will cause a force.

T = F * r * sin(theta)

When a wire is twisted, a torque is applied to it.

k = T / theta

torsional stiffness

internal magnetic field created by a very long current-carrying wire

F = μ₀I₁I₂L / 2πd

force between the wires

Biot-Savart Law

it states that the magnetic field at a point is proportional to the current density and the distance from the point to the current element.

Ampère's Law

The law states that the line integral of the magnetic field around a closed loop is equal to the current passing through the loop multiplied by a constant known as the permeability of free space.