Electric Charge and Fields Overview

Study Notes

Electric Charge

Electric charge is a fundamental property of matter.
Two types of electric charge exist: positive and negative.
Like charges repel; unlike charges attract.
The unit of electric charge is the coulomb (C).
Protons have a positive charge, electrons have a negative charge, and neutrons have no charge.
Charge is conserved; it cannot be created or destroyed, only transferred.

Electric Field

An electric field is a region of space around a charged object where another charged object experiences a force.
Electric field strength is measured in Newtons per coulomb (N/C).
Field direction is the force a positive test charge would experience at that point.
Electric field lines radiate outward from a positive charge and inward toward a negative charge.
Field strength decreases with distance from the charge.

Electric Potential

Electric potential (voltage) is the work done per unit charge to move a charge from a reference point to a specific point in an electric field.
The unit of electric potential is the volt (V).
The electric potential difference (voltage) between two points is the difference in electric potential between those two points.

Current

Electric current is the rate of flow of electric charge.
The unit of electric current is the ampere (A), which equals one coulomb per second.
Current flows from higher potential to lower potential.
Conventional current is the direction of positive charge flow. Electron flow is opposite.

Resistance

Resistance measures how difficult it is for electric current to flow through a material.
The unit of resistance is the ohm (Ω).
Resistance depends on the material, length, cross-sectional area, and temperature of the conductor.

Ohm's Law

Ohm's Law states that current through a conductor is directly proportional to the voltage across the two points.
Mathematically expressed as: V = IR, where V is voltage, I is current, and R is resistance.

Power

Electric power is the rate at which electric energy is transferred or used.
The unit of electric power is the watt (W), which equals one joule per second.
Power calculations include P = IV, P = I²R, and P = V²/R.

Direct Current (DC)

Direct current (DC) is the flow of electric charge in one direction.
Batteries are a common DC source.
In DC systems, current flows consistently from positive to negative.

Alternating Current (AC)

Alternating current (AC) is the flow of electric charge that periodically reverses direction.
AC is generated by alternators and transformers.
AC is widely used for power distribution because it can be easily transformed to different voltages.

Conductors, Semiconductors, and Insulators

Conductors allow the free flow of electric charge.
Semiconductors have conductivity between that of a conductor and an insulator.
Insulators restrict the flow of electric charge.

Description

This quiz covers fundamental concepts of electric charge, electric fields, and electric potential. Understand the distinctions between positive and negative charges, the behavior of charges, and how electric fields interact with charged objects. Test your knowledge about these essential components of electrical science.