JEE · Physics · Electrostatics doubts

What does “Coulomb's law” actually mean in Electrostatics, and why does it matter for JEE?

the force between two point charges, F = kq₁q₂/r², along the line joining them.

I keep getting “Coulomb's law” questions wrong in Electrostatics. What's the trap?

ignoring that like charges repel and unlike attract when assigning direction.

What does “Electric field” actually mean in Electrostatics, and why does it matter for JEE?

the force per unit positive charge, E = F/q; field lines point away from positive charges.

I keep getting “Electric field” questions wrong in Electrostatics. What's the trap?

treating field (a vector) and potential (a scalar) as the same thing.

What does “Electric potential” actually mean in Electrostatics, and why does it matter for JEE?

the work done per unit charge to bring a charge from infinity to a point, V = kQ/r.

I keep getting “Electric potential” questions wrong in Electrostatics. What's the trap?

thinking zero field means zero potential (or vice versa).

What does “Capacitance” actually mean in Electrostatics, and why does it matter for JEE?

a capacitor's ability to store charge per volt, C = Q/V; for parallel plates C = ε₀A/d.

I keep getting “Capacitance” questions wrong in Electrostatics. What's the trap?

forgetting a dielectric increases capacitance.

What is the difference between electric field and electric potential?

Field is a vector (force per charge, N/C); potential is a scalar (energy per charge, volts) — field points from high to low potential.

What is the difference between capacitors in series and capacitors in parallel?

In series the charge is the same and 1/C adds (total C smaller); in parallel the voltage is the same and C adds (total C larger).

What is the difference between conductor and insulator?

A conductor has free charges that move easily; an insulator holds its charges in place.

When do I use F = kq₁q₂/r² in Electrostatics, and what does it mean?

Coulomb force between point charges.

When do I use E = kQ/r² in Electrostatics, and what does it mean?

field of a point charge at distance r.

When do I use V = kQ/r in Electrostatics, and what does it mean?

potential of a point charge.