#5: Point Charges

These flashcards cover key concepts of electric fields and point charges, focusing on equations, principles, and applications discussed in the lecture.

What is the equation for electric field strength near a point charge?

E = Q/(4πεr^2)

Why is electric field strength E equal to zero inside a charged sphere?

Inside a charged sphere, the electric field cancels out due to symmetry.

What does it mean to consider an object as a point charge?

A point charge is an expression used when the distances involved are much greater than the size of the object.

What does Coulomb's law state about the force between two point charges?

Coulomb's law states that the force F on a test charge q at distance r from a point charge Q is F = (1/(4πε))*(Qq/r^2).

How does the electric field strength vary with distance r from a point charge?

The electric field strength E is inversely proportional to the square of the distance r.

What is the relationship between electric potential V and distance r from a point charge?

The electric potential V is inversely proportional to the distance r from the charge.

What is the value of the electric field strength at distance r from a point charge?

E = Q/(4πεr^2)

How does the electric field strength behave near a negatively charged object?

E gives a negative value, indicating the field lines point inwards towards the charge.

What occurs at the tip of a lightning conductor during a storm?

The electric field becomes so strong that the air molecules near the tip are ionized, allowing air to conduct electricity.

How is electric field strength related to the potential gradient?

Electric field strength E = - (dV/dx), where dV/dx is the potential gradient.

What is the significance of a negative electric potential?

Negative electric potential indicates a value less than zero, affected by the sign of the charge.

What equation represents the change of potential in an electric field?

Change of potential = area under an electric field strength versus distance graph.