Forces
What is a field force?
A field force is any force that can be exerted by an object on another without the two objects having to touch
Describe the process of charging by contact
Rubbing two unlike materials together tends to charge both of them, as electrons flow from one object into another
Materials through which electrons do not freely flow are called...
Insulators
What is a test charge?
A small, positive charge
A repellant force occurs between two charges when they are...
The same sign
Name two field forces
Electric force and gravitational force
Object A and Object B are rubbed together to create a negative charge on Object A and a positive charge on Object B. What can you say about the magnitude of the charge on Object A?
It will be equal to the magnitude of the charge on Object B.
Materials through which electrons flow freely are called...
Conductors
Is an electric field stronger 20 cm away from the source charge or 30 cm away from the source charge?
20 cm
What does it mean that electric charge is conserved?
Any charge gained by one object will be lost from another object- charge is not created or destroyed.
Which is stronger: gravitational force or electric force?
Electric force
When a rubber balloon (insulator) is charged by rubbing it on hair, does the whole balloon get charged or just the area that touches the hair? Why?
Just the area that touches the hair, because electrons do not flow freely in an insulator.
This method of charging can be done to both insulators and conductors
Charging by contact
In a field diagram, should electric field lines point towards or away from a positively charged object?
Away from
What two factors determine the strength of an electric field?
1. The magnitude of the charge creating the field
2. The distance from the charge
What are two differences between electric force and gravitational force?
1. Electric force is stronger
2. Electric force can be either attractive or repulsive, while gravitational force can only be attractive
Describe the process of polarization
A charged object placed near an insulator causes the molecules on the insulator's surface to gain a partial charge on each side, creating a slight surface charge on the insulator
When a conductor is in electrostatic equilibrium, what is one place where charge accumulates?
1. The surface of the conductor (always)
2. Pointed areas (more charge accumulates than in rounded areas)
In a field diagram, should electric field lines point towards or away from a negatively charged object?
Towards
What has occurred when the molecules on the surface of an object have a partial charge on each side?
Polarization
When two charges are moved closer together, how does the force acting between them change?
It becomes stronger
Describe the process of induction
1. A charged object is placed near a conductor
2. Conductor is grounded
3. Charge flows out through ground
4. Ground is removed
5. Charged object can now be removed
When a conductor is in electrostatic equilibrium, what must be true of the electric field directly outside the conductor?
The electric field outside the conductor must be perpendicular to the surface of the conductor
Charge A is twice as strong as charge B. In a field diagram, charge A will have ___________ as many field lines going in/out of it as B.
Twice
How do you calculate the resultant force when multiple charges are exerting force on a charge?
The vector sum of each force vector is the resultant force.