6 Questions
What is the formula for torque experienced by an electric dipole placed in a uniform electric field?
$\tau = pE \sin \theta$
What is the force between two small charged spheres with charges of 2 × 10^-7 C and 3 × 10^-7 C when placed 30 cm apart in air?
0.24 N, repulsive
What is 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?
0.2 N, repulsive
What are the important points of Glauss's law?
It relates the electric flux through a closed surface to the charge enclosed by the surface
If 109 electrons move out of a body every second, how much time is required to transfer a total charge of 1 C to another body?
625 seconds
What are the electric field lines characteristics?
They originate from positive charges and terminate on negative charges
Study Notes
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.
This physics unit test for class 12 covers topics such as characteristics of electric field lines, Coulomb's law in vector form, torque for electric dipoles, and Gauss's law. The test consists of 5 questions with a total of 20 marks to be completed in a 3-hour time frame.
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