Module 6.2 Flashcards
Coulomb’s Law
The size of the force that acts between two point charges is
proportional to the product of their charges and inversely proportional to the
square of their separation. It is attractive for opposite charges and repulsive for
like charges.
Electric Field Strength
The force per unit positive charge exerted on a charged
object placed at that point in the field. This is a vector acting in the same direction
as the force on a positive charge
Electric Field
A region surrounding a charged object which causes a force to be
exerted on any charged object placed within the field.
Electric Potential Energy
The work done on a positive charge in bringing it from
infinity to that point in the field. It is proportional to the product of the two charges
and inversely proportional to their separation.
Electric Potential
The work done per unit charge on a positive test charge in
bringing it from infinity to that point in the field
Field Lines
Lines that demonstrate the direction in which a positive charge would
feel if placed at that point in the field
Parallel Plate Capacitor
A capacitor made up of two parallel conducting plates
with an insulator between them (dielectric).
Permittivity
A property of an electric field. It relates electric flux density and the
electric field strength.
What shape of field do point charges have
Radial fields
How can you model uniformly charged spheres
As a point charge at the center of the sphere
What do field lines show
The path a positive test charge would take when placed in an Electric Field
Which direction do the field lines point
Positive to negative - the lines always point away from a positive charge and towards a negative charge
What effect does distance have on the strength of the electrostatic force
The greater the distance, the weaker the force
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
list 3 similarities between Gravitational and Electric field
- Both follow the inverse square law for the force
- Point masses and point charges both produce a radial field
- Field strength is defined by force per unit charge/mass
Give 2 differences between Gravitational and Electric fields
- Gravitational fields are always attractive, Electric fields can be attractive or repulsive depending on the charge
- The constants of proportionality in Newton’s Law and Coulomb’s Law are different
Define potential at a point in an Electric field
The work done per unit charge in moving a positive test charge from infinity to that point in the Electric field
What can the motion of charged particles in an Electric field be modelled as
Projectile motion: the two components of velocity are independent to each other
- Velocity perpendicular to the field is not affected by the field, the velocity parallel to the field is
How do you calculate the parallel component of velocity for a charged particle in a uniform Electric field
1) Calculate the time the particle is in the field (using time = distance/speed where distance = length of charged plates and speed = velocity perpendicular to the field)
2) Use a =F/m and F=Eq to calculate the acceleration of the particle while it is in the field (a = Eq / m)
3) Sub these values into V = u +at where u is initial parallel velocity and V is the final parallel velocity
What does the force-distance graph for a point/spherical charge look like
Decreaingly exponential graph
Force is inversely proportional to the square of the distance
What does the area under a force-distance graph for a point/spherical charge represent
The work done in moving the charge
