Coulomb’s Law

Physics ⇒ Electricity and Magnetism

Coulomb’s Law starts at 9 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Coulomb’s Law. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.

See sample questions for grade 10

A charge of +5 μC is placed 0.2 m from a charge of -2 μC in air. Calculate the magnitude of the force between them. (k = 9 × 10⁹ N·m²/C²)

Calculate the force between two charges of +1 C each placed 1 m apart in vacuum. (k = 9 × 10⁹ N·m²/C²)

Describe how the medium between two charges affects the electrostatic force between them.

Describe the effect of the sign of charges on the direction of the force between them.

Explain why Coulomb’s Law is called an inverse square law.

If the distance between two charges is increased by a factor of 3, by what factor does the force change?

If the force between two charges is F, what will be the force if the distance between them is reduced to half?

State Coulomb’s Law.

The force between two charges in air is 5 N. If the same charges are placed in a medium with dielectric constant 5, what is the new force?

The force between two charges is 10 N. If the magnitude of each charge is doubled, what will be the new force?

Two charges exert a force of 2 N on each other. If one charge is tripled, what is the new force?

Two charges of +2 μC and +3 μC are placed 0.5 m apart in vacuum. Calculate the force between them. (Take k = 9 × 10⁹ N·m²/C²)

What happens to the force between two charges if both charges are negative?

What is the value of Coulomb’s constant (k) in SI units?

Which law governs the force between two stationary point charges?

Write the mathematical formula for Coulomb’s Law.

A charge of +8 μC is placed at the origin, and a charge of -2 μC is placed at x = 0.4 m on the x-axis. Calculate the force on the -2 μC charge, stating its magnitude and direction. (k = 9 × 10⁹ N·m²/C²)

Explain why Coulomb’s Law cannot be used to calculate the force between two charged spheres if their sizes are not negligible compared to the distance between them.

If the force between two charges in air is F, what will be the force between the same charges if they are placed in a medium with relative permittivity ε_r?

State two limitations of Coulomb’s Law.