Static Electricity, Charge, and Fields Quiz Flashcards
Static Electricity
Stationary electricity, study of charges at rest and the interactions between them
how can you think of an electric field
one charge creates a field, a second actualizes the electric force.
how do charged objects exert a force
by changing the space around them
Electric Field
the force field, the changed property of space around a charged object
units of the electric field
N/C (newtons/coulomb)
is electric field vector or scalar?
vector
The electric field on an object is
the amount of electric force exerted per unit of charge.
what is the equation for electric field
Electric & Gravitational Fields Compared
how is E similar to g
Just like a mass in a gravitational field, the electric force that is exerted on a charge in an electric field depends on the magnitude of the electric field.
what is another way to calculate the strength of an electric field
use the magnitude of the charge that creates the field
Electric Field Map
A set of electric field lines representing the electric field around a charged object
The direction of the electric field lines represents
the direction of the electric force on a positive test charge
The density of the field lines represents
the strength of the electric field
true or false: Electric Field lines never cross
true
Electric Field to Charged parallel plates
Electric Field Due to 2 positive Charges
Electric Field Due to a Dipole
The arrows show
the direction of motion/force for a positive charge
A dipole
a pair of charged particles that have equal but opposite charges
electric field around a point charge (positive or negative)
An electric field is said to exist where?
anywhere an electric force is felt. Placing a positive test charge in a field and observing its path creates a segment of a “field map.”
what is the unit of charge
coulomb
true or false: protons and electrons have equal charges (same magnitude)
true
1 coloumb is equal to?
C=6.24x 10^18 e
an electron is equal to
1.6x10^-19 C
coloumb’s law
the force btw. 2 charges is equal to some constant times the first charge times teh second charge divided by distance between them squared
what is the symbol for charge
q
charged object
has unequal amounts of positive and negative charge
Neutral object
has equal amounts of positive and negative charge
is charge scalar or vector
scalar
is charge conserved
Charge is conserved: when charge is transferred between objects equal amounts of charge are separated (the gain in + charge of one object= the gain in –charge of the other)
properties of charge (list 6)
- Two types of charge: positive and negative (charge is a scalar)
- Charge is conserved: when charge is transferred between objects equal amounts of charge are separated (the gain in + charge of one object= the gain in –charge of the other)
- Charges have an effect over a distance
- Charge is quantized: the smallest possible charge an object can have is the charge of a proton or electron (+/- 1.6 x 10-19 C)
- Objects with like charges repel, objects with opposite charges attract
- Materials vary in their ability to hold charge(insulators/conductors)
Conductors
don’t hold charge well (allow electrons to move freely)
exs of conductors
Aluminum
Gold
Copper
All Metal
You!
Insulators
hold charge well (don’t allow electrons to move freely)
exs. of insulators
Plastics
Ceramics
Cloth
How can we charge objects?
Objects can be charged in 3 different ways: friction, conduction, and induction
Charging by Friction
When objects made from different insulating materials are rubbed together, electrons are transferred from one to the other
Ex:
- a balloon and wool
- hair and a plastic comb
- glass and silk
Charging by conduction
2 conducting objects, with different net charges, come in contact with each other, causing electrons to move from one to the other
Ex:
- two copper wires
- a human hand and a charged metal object
Charging by Induction
A charged object is brought close to a conducting neutral object, causing the electrons in the neutral object to be rearranged
The neutral object becomes polarized (no net charge, but electrons and protons are unevenly distributed in the object)
If one side of the object is then grounded (connected to a source of infinite charge) it becomes charged overall
Electric Force
A force of attraction or repulsion between charged objects
A field force
Depends on the amount of charge, the type of charge, and the distance separating the objects
Smaller distance greater force
More charge greater force
