Electric fields Flashcards
(28 cards)
What does Couloumb’s law state
Magnitude of 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
Types of electric fields
Uniform and radial
What is the squiggly e in terms of electric field
Permittivity of free space
What is r in terms of the couloumb law formula
Distance between charges
When will the force in an electric field be positive or negative
Same sign then repulsive, different signs then attractive
Size of electrostatic forces compared to gravitational
Electrostatic force between subatomic particles is magnitudes greater than gravitational forces because the masses of subatomic particles are ver small whilst their charges are much larger
How much bigger is the the electrostatic force between 2 protons than the gravitational one
1.24x10^36
What is the electric field strength
Force per unit charge experienced by an object in an electric field
How does the electric field strength vary in a uniform vs radial electric field
Constant in uniform, varies in radial
Formula to find electric field strength in either a uniform or radial field
E = F / Q
Which direction to electric fields flow
Positive to negative
How can the work done in an electric field be derived
Moving a charged particle between the parallel plates of a uniform field
What is the equation to find the work done by moving a charged particle between the parallel plates in a uniform field
Work done = Q / (change in V)
What happens when you fire a particle at right angles to a uniform electric field and how can you tell if it is charged / what charge is has
Charged particle will follow a parabolic shape, if charge is positive then it follows direction of field, if negative then moves opposite to direction of the field
What is absolute electric potential at a point
Potential energy per unit charge of a postive point charge at that point in a field
Where is the absolute magnitude of electric potential biggest
At the surface of a charge
Relationship between distance from charge and absolute electric potential
Bigger distance means a smaller absolute electric potential
At what point in a field is the absolute electric potential zero
Infinity
Electric potential formula in a radial field
V = 1 / (4(pi)(squiggly e 0)) x (Q / r)
Potential and force on a positive charge in an electric field
Positive potential, repulsive force
Potential and force on a negative charge in an electric field
Negative potential, attractive force
Is absolute electric potential negative or positive when the charge is positive
Positive
Is absolute electric potential negative or positive when the charge is negative
Negative
Gradient of a tangent to an electric potential against distance graph
Electric field strength
