Chapter 22 - Electric Fields Flashcards
What is Coulomb’s Law?
Coulomb’s law states that the magnitude of the force between two point charges in a vacuum is directly proportional to the product of their charges, and inversely proportional to the square of the distance between the charges.
How does the magnitude of electrostatic forces on subatomic particles compare to the magnitude of gravitational forces?
The magnitude of electrostatic forces between subatomic particles is much greater than the magnitude of gravitational forces (masses are very small in proportion to charges).
What is electric field strength?
Electric field strength (E) is the force per unit charge experienced by an object in an electric field.
How does electric field strength change in different fields?
This value is constant in a uniform field, but varies in a radial field.
What do field lines show?
Field lines show the direction of force acting on a positive charge.
What is the difference between uniform and radial fields? (With relation to electric force)
For a uniform field, the electric force is the same everywhere (as shown by parallel and equally spaced lines).
For a radial field, the magnitude of electric force depends on the distance between the two charges.
Uniform fields can be used to find the charge of a particle, by firing a particle at right angles to the field and observing its path.
Uniform fields can be used to find the charge of a particle, by firing a particle at right angles to the field and observing its path.
What is electric potential?
Absolute electric potential (V) at a point is the potential energy per unit charge to move a positive point charge from infinity to that point in the field.
How does electric potential change with distance?
The absolute magnitude of electric potential is greatest at the surface of a charge, and as distance increases, potential decreases. The electric potential at infinity is zero.
What is electric potential difference?
Electric potential difference is the energy needed to move a unit charge between two points.
What is an equipotential surface?
An equipotential surface is where potential is the same everywhere. When a charge moves along an equipotential surface, no work is done.
How can you find electric field strength using a graph of V against r?
The gradient of a tangent to a potential (V) against distance (r) graph gives the electric field strength at that point.
How can you find electric potential difference using a graph of E against r?
Electric potential difference is equal to the area under a graph of electric field strength (E) against distance (r).
