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 11

A charge of +4 μC is placed at the origin and another charge of +6 μC is placed at x = 3 m. Calculate the force on the +6 μC charge. (k = 9 × 10⁹ N·m²/C²)

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)

A charge of 1 C is placed 1 m away from another charge of 1 C in vacuum. Calculate the force between them. (k = 9 × 10⁹ N·m²/C²)

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

Describe the effect of increasing the magnitude of one of the charges on the electrostatic force between two charges.

Describe the superposition principle as it applies to electrostatic forces.

Explain how the electrostatic force changes if the medium between two charges is changed from air to water.

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

If the force between two charges is F in air, what will be the force between them in a medium of dielectric constant K?

If three charges are placed at the corners of an equilateral triangle, explain how you would find the net force on one of the charges.

If two charges exert a force of 10 N on each other, what will be the force if the distance between them is reduced to half?

State Coulomb’s Law and write its mathematical expression.

Two charges, +q and -q, are placed 1 m apart in air. What is the nature of the force between them?

What is the effect of the dielectric constant of a medium on the electrostatic force between two charges?

A charge of +3 μC is placed at the origin, and a charge of -3 μC is placed at (0, 4 cm) on the y-axis. Calculate the magnitude and direction of the force on the charge at the origin. (k = 9 × 10⁹ N·m²/C²)

A point charge q₁ exerts a force F on another point charge q₂ at a distance r in vacuum. If both charges are doubled and the distance between them is halved, what will be the new force between them in terms of F?

A third charge, +2 μC, is placed at the midpoint between two charges, +6 μC and -6 μC, which are 10 cm apart in vacuum. Calculate the net force acting on the +2 μC charge. (k = 9 × 10⁹ N·m²/C²)

Explain why the electrostatic force between two charges is considered a conservative force.

Suppose two identical point charges are fixed at a distance d apart. A third charge is placed exactly midway between them. If all three charges are positive, describe the direction of the net force on the third charge and explain why.

Two point charges, +8 μC and -5 μC, are placed 0.4 m apart in a medium with a relative permittivity (dielectric constant) of 2. Calculate the magnitude and nature (attractive or repulsive) of the force between them. (k = 9 × 10⁹ N·m²/C²)