Electric Charge and Its Properties

Electric Charge

• Electric charge is a fundamental property of matter existing in two forms: positive and negative.
• Like charges repel, unlike charges attract.
• The fundamental unit of charge is the Coulomb (C), a large unit in everyday experience.
• Charge is quantized; it exists in discrete units of multiples of the elementary charge (e), approximately 1.602 x 10^-19 C.
• The total charge of a closed system is conserved; charge cannot be created or destroyed, only transferred.
• Conductors allow free charge movement; insulators hinder it.

Properties of Electric Charge

• Charge is a scalar quantity.
• Charge is additive.
• Charge is conserved.
• Charge is quantized.

Methods of Charging

• Charging by friction: Electron transfer through rubbing.
• Charging by conduction: Electron transfer through direct contact with a charged object.
• Charging by induction: Charge separation in a neutral object caused by a nearby charged object, without direct contact.

Electric Field

• An electric field is a region around a charged object where another charged object experiences a force.
• The electric field is a vector field, with magnitude and direction at every point.
• The electric field direction is the force a positive test charge would experience.
• The field's magnitude depends on the source charge and distance from it.
• Electric field lines visualize the field, originating on positive and terminating on negative charges. Line density corresponds to field strength.

Electric Field Strength

• Electric field strength (intensity) is the force per unit positive charge on a test charge.
• Measured in Newtons per Coulomb (N/C).
• The electric field strength due to a point charge is given by Coulomb's Law.

Coulomb's Law

• Coulomb's Law describes the force between two point charges.
• The force is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them.
• The force is attractive for opposite charges, repulsive for like charges.
• The force is along the line joining the charges.
• Formula: F = k |q₁q₂|/r², where k is Coulomb's constant, q₁ and q₂ are the charges, and r is the distance between them.

Electric Field due to a Point Charge

• The electric field due to a point charge at a distance r is: E = k|q|/r².

Superposition Principle for Electric Fields

• The total electric field at a point due to multiple charges is the vector sum of the electric fields due to each individual charge.

Electric Field Lines

• Electric field lines never cross.
• Electric field lines originate on positive charges and terminate on negative charges.
• The closer the field lines, the stronger the electric field.

Electric Potential

• Electric potential (V) is electric potential energy per unit charge.
• A scalar quantity, measured in Joules per Coulomb (J/C), or Volts (V).
• Electric potential at a point is the work done per unit positive charge to bring a test charge from infinity to that point.
• Potential difference is the difference in electric potential between two points.

Electric Potential Difference

• Electric potential difference between two points is the work done per unit charge in moving a charge between them.
• Also called voltage (V).
• Measured in Volts (V).

This quiz covers the fundamental concepts of electric charge, including its properties, methods of charging, and the behavior of positive and negative charges. Understand how charge conservation plays a crucial role in electrical systems and the differences between conductors and insulators.