Explain how a source charge exerts force on another charge (4-story)
An electric field is said to exist in the region of space around a _______ _______ (______ ______). The existence of an electric field is a property of the _______ ______.
When another charged object, the ______ ______, enters the electric field, an electric force (________ force) acts on it. The presence of the ______ charge is not necessary for the field to exist
- charged object (source particle)
- source charge
- test charge
- Coulomb's force
- test charge
1. The test particle is used to detect the existence of the ______. So it is a detector of the ______. By convention, the test particle is always a _______ _______ ______.
2. It is also used to evaluate the ______ of the field
3. The test charge is assumed to be small enough not to disturb the _______ _______ responsible for the field
- positive electric charge
- charge distribution
Define electric field
Define electric field vector at a point in space and state the units/explain Magnitude E
- Electric Field: the electric force on the test charge per unit charge
State the formulas (explain the components) for:
Vector F as it pertains to Vector E
Under Gravitational Force, state
Newton's law for force
The Gravitational constant
The Gravitational Field formula and its units
Under Electrostatic Force, state:
Coulomb's law for force
Coulomb's constant ke
Formula for the Electric field (vector) and its units
Once the field is known at some point, the force on any particle with any charge q placed at that point can be calculated from:
vector Fe = ?
If the probe charge q is positive, what will the direction of the Electric field vector be?
If the probe charge q is negative, what will the direction of the Electric field vector be?
(a) Charge q is placed at two different points in space. The force on the charge tells us that there's an ______ ______ at these points
(b) Label the diagram
- electric field
At any point P, the total electric field due to a group of source charges equals the _____ _____ (of) ______ ______ at that point due to all the particles. State the formula
- vector sum of electric fields
- A. → + → = ↠
- B. ↞ + → = ←
- C. ↞ + ← = ↞ *longest
- D. ↞ + ↠ = 0 *shortest
- 1. A has the greatest field strength because it is closest to the source with the most field lines around it
- 2. D has the smallest field strength because it farthest from the source with the greatest distance between surrounding field lines
A dipole consists of a _______ and _______ charge separated by a short distance. The dipole has no _____ ______, but it does have a net ______ _______.
What is the charge value of the dipole electric field at each of these points:
- positive and negative
- no net charge
- net electric field
Parallel-plate capacitor consists of _____ conducting plates, called _______. They are face to face with a narrow gap between them.
One electrode has total charge _____ and the other has total charge _____.
Electric field inside the parallel-plate capacitor is constant in both ______ and ______ (state the formula for Ecapacitor and the direction of the parallel plate capacitor)
- strength and direction
Parallel Plate Capacitor
The plates are ______ compared to the distance between them.
The cross-section view shows a small region near the center of the plates far from the edges. How do the charges end up on the inner surfaces of the plates?
- Because the opposite charges attract, pulling them to the inner surfaces of the plates
_____ _____ give us a means of representing the electric field pictorially.
The electric field vector is ______ to the electric field line at each point.
The line has a direction that is the same as that of the ______ _______ ______
The lines at different locations point in _______ directions causing a ________ ______ field
- Field lines
- electric field vector
- different directions
- nonuniform E field
For a positive point charge, the field lines are directed _______ _______
For a negative point charge, the field lines are directed _______ _______
Rules for Drawing Electric Field lines
Field lines are _________ to the surface
Number of field lines per unit area through the ________ surface is ________ to the magnitude of the electric field in that region
Field lines are closer together if E is ______ and are farther apart if E is ______
Lines must begin on _______ charges and end on _______ charges. In case of an excess of one type of charge, some lines will begin or end _______ far away.
Fields cannot _______
For a conducting surface, make sure the field lines are _______ distributed (so as a point charge)
- perpendicular surface
- positive charges
- negative charges
- infinitely far away
- evenly distributed
(a) Relationship between field vectors and field lines
The electric field vector is ______ to the electric field line
The electric field is stronger where the electric field vectors are ______ and where the electric field lines are ______ _______
(b) Field lines of a positive point charge
The field is directed away from the ______ charge, so the field lines are directed radially _______.
The field lines are closest together near the charge, where the field strength is ________
(c) Field lines in an ideal capacitor
The field vectors are directed from the ______ to ______ plate, so the field lines are as well.
The field is constant, so the field lines are _______ _______
- closer together
- positive charge
- radially outward
- positive to negative plate
- evenly spaced
The dipole occurs when two points of _____ magnitude and ________ signs are separated by a short distance. The number of the field lines leaving the positive charge equals the number terminating at the ________ charge
For two charges +2q and -q.
Two field lines leave ____ for every one that terminates on _____
- equal magnitude
- opposite sign
- negative charge
When there is no ____ _____ of charge within a conductor, the conductor is said to be in electrostatic equilibrium. Every charge in the conductor is a particle in ________. They experience _____ net force
The charges are _____ _____ and the electric field is strongest at the ______ end of a conductor
- net motion
- zero net force
- closer together
- pointed end
Properties of electrostatic equilibrium:
1. The electric field is ______ everywhere inside the conductor.
2. If an isolated conductor carries a charge, the charge resides entirely on its ______.
3. The electric field just outside a charged conductor is _______ to the surface and has a magnitude of ______
4. On an irregularly shaped conductor, the surface charge density is greatest at locations where the radius of the curvature is ________
Explain what is depicted and state the electric field value inside the void
If an electric dipole is placed in a uniform electric field, the dipole experiences no _____ ______.
But there is a _____ _____ on the dipole that causes it to rotate.
Define the electric dipole moment
State the formula for the magnitude of the dipole moment and explain the components.
The rotation will align the dipole moment with the ______
- no net force
- net torque
- Electric Dipole Moment:
- Magnitude of a dipole moment, P = Qd
- Q: charge of the dipole
- d: the separation between +Q and -Q
When the dipole lines up with the field, the net torque is ______. The dipole is in ______ _______. We can say that the _____ _____ tries to align itself with the field
- static equilibrium
- dipole moment