Physics Unit Test: Chapters 1, 2 - Class 12 Jeni Classes

Torque and Electric Dipoles

• The formula for torque experienced by an electric dipole placed in a uniform electric field is τ = p × E, where τ is the torque, p is the dipole moment, and E is the electric field.

Coulomb's Law and Electrostatic Forces

• The force between two small charged spheres with charges of 2 × 10^-7 C and 3 × 10^-7 C, placed 30 cm apart in air, can be calculated using Coulomb's Law.
• The electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge -0.8 µC in air, if the distance between them is 10 cm, can be calculated using Coulomb's Law.

Gauss's Law

• Important points of Gauss's Law include:
  • The total electric flux through a closed surface is proportional to the charge enclosed within the surface.
  • The law relates the distribution of electric charge to the resulting electric field.
  • It is a fundamental principle in the study of electromagnetism.

Electric Charge and Time

• If 109 electrons move out of a body every second, the time required to transfer a total charge of 1 C to another body can be calculated by dividing the total charge by the rate of charge transfer.

Electric Field Lines

• Electric field lines are characterized by:
  • They emerge from positive charges and enter into negative charges.
  • They are continuous and unbroken, forming a loop if the charge is isolated.
  • They never intersect each other, as they represent the direction of the electric field at a given point.