Electric fields Flashcards
What is an electric field?
The space around a charge where an electric force is experienced.
What does the direction of electric field lines indicate?
The direction of force on a positive charge, always from positive to negative.
What does the density of electric field lines indicate?
A higher density means a stronger electric field.
What does Coulomb’s Law state?
The force between two charges is proportional to the product of the charges and inversely proportional to the square of their separation.
What is the formula for Coulomb’s Law?
F = k Q_1 Q_2 / r^2
What is the value of Coulomb’s constant k?
k = 1 / (4πε_0) = 8.99 × 10^9 Nm²C⁻²
What is the permittivity of free space ε_0?
8.85 × 10⁻¹² Fm⁻¹
What is the formula for the electric field of a point charge?
E = kQ / r²
How is electric field strength related to force?
E = F / q, where F is the force and q is the charge.
What is electric potential?
The work done in bringing a unit positive charge from infinity to a point.
What is the formula for electric potential due to a point charge?
V = kQ / r
What is the relationship between work done and electric potential?
W = VQ
What is the formula for potential difference between two points A and B?
V_AB = Q / (4πε_0) (1/b - 1/a)
What happens to electric potential energy if a negative charge moves in the direction of the electric field?
Its electric potential energy decreases.
What happens to electric potential energy if a positive charge moves in the direction of the electric field?
Its electric potential energy increases.
What is electric potential energy?
The ability of a charged particle to do work due to its position in the field of another charged particle.
What is the formula for electric potential energy?
U = kQq / r
How is electric potential energy related to kinetic energy?
Vq = 1/2 mv²
Where is charge distributed on a conducting sphere?
Uniformly on its surface.
What is the electric field inside a charged conducting sphere?
Zero.
What is the electric potential at any point inside a charged hollow sphere?
The same as at the surface.
What is an equipotential surface?
A surface where the electric potential is constant.
What is the relationship between electric field lines and equipotential surfaces?
They meet at right angles.
What happens when a charge moves along an equipotential surface?
No work is done.
Where does a uniform electric field exist?
Between two parallel plates with opposite charges.
What is the formula for force in a uniform electric field?
F = Vq / d
What is the relationship between voltage and electric field in a uniform field?
V = Ed
How are electric and gravitational potential similar?
Both are ratios of work done to charge/mass, and both have zero potential at infinity.
How do electric and gravitational forces differ?
Gravitational forces are always attractive, but electric forces can be attractive or repulsive.
What happens when two like electric charges come together?
Work is done on the charges (energy is required).
What happens when two opposite electric charges come together?
Work is released (energy is gained).
