Chapter 22: Electrical Fields Flashcards
Electric Field
A region of space in which charged particles are subject to an electrostatic force
What shape of field do point charges have?
Radial fields
How can you model uniformly charged spheres?
As a point charge a the centre of the sphere
What do field lines show?
The path a positive charge would take when placed in an electric field
What direction do field lines point?
Positive to negative
What effect does distance have on the strength of the electrostatic force
The greater the distance, the weaker the force
Inversely square relation
How is the strength of an electric field represented in a diagram?
By how close together the field lines are - the closer the lines the stronger the field
Electric field strength
Force per unit charge on a positive charge placed in a field
What is the formula for electric field strength
E = F/Q
Coulomb’s Law
The force between any two point charges is proportional to the product of their charges and inversely proportional to the square of the distance between them.
Permittivity
The ability of a material to transmit an electric field (how easily atoms become polarised)
What are the similarities between gravitational and electric fields
- both follow inverse square law
- point masses and point charges both produce radial fields
- Newton and Coulomb law similar
- Field strength as force per unit mass/charge
What are the differences between gravitational and electric fields
- grav are always attractive, elec can be both
- different constants
What is the formula for the work done when moving a charge in an electric field
Work done = force x distance
Define Potential at a point in an electric field
The work done per unit charge in moving a positive charge from infinity to that point in an electric field
