Physics II: Classical Mechanics and Electricity

Electric Charge and Coulomb's Law

• The space around a charged particle within which a force would be exerted on other charged particles is called an electric field.
• There are two types of electric charges: positive and negative.

Charge Interactions

• When charges of the same sign (both positive or both negative) interact with each other, they repel each other.
• When charges with opposite signs (one positive and one negative) interact with each other, they attract each other.
• The factor that determines whether two charged rods will attract or repel each other is the type of charge they possess (same or opposite).

Units of Electric Charge

• The unit of electric charge is the coulomb (C).
• The fundamental unit of charge is the elementary charge (e), which is the charge of a single proton or electron.

Coulomb's Law

• The electric force exerted by one charge on another charge is a vector force.
• According to Coulomb's Law, the force between two charged particles is inversely proportional to the square of the distance between them.
• The SI unit of charge is the coulomb (C).
• If the distance 'r' between two charged particles doubles, the force is reduced to one-quarter of its original value.
• If the charges of the particles double, the force between them quadruples.

Constants and Symbols

• The value of the Coulomb constant 'k' is 8.98755 × 10^9 N m^2 C^−2.
• The quantized unit of charge represented by 'e' is 1.602 × 10^−19 C.
• The permittivity of free space represented by the symbol 'ε₀' is 8.85418781762039 × 10^−12 F/m.
• The symbol 'q' represents the electric charge of a particle.

Forces and Vectors

• The resultant force on any one charge equals the vector sum of the forces exerted by all other charges.
• The electric force exerted by one charge on another charge is directed along the line joining the two charges.