Chapter 6: Electrostatics Flashcards
Electrostatics is:
the study of stationary charges and the forces that are created by and act upon these charges
Proton charge:
positive
Electron charge:
negative
Opposite charges exert what kind of forces?
attractive
Like charges exert what kind of forces?
repulsive
The SI unit of charge is the:
Coulomb [C]
The fundamental unit of charge (e) is:
e = 1.6 X 10-19 Coulombs
The charge of one proton and the charge of one electron are equal to:
1.6 X 10-19 Coulombs; protons are positive, electrons are negative
Coulomb’s law gives us:
The magnitude of the electrostatic force F between two charges q1 and q2 whose centers are separated by a distance r.
The equation used to determine the attractive or repulsive force two charges exert on one another:
F = kq1q2 / r2;
where k = 8.99 X 109 NM2/C2; q1 and q2 are in Coulombs; r is in meters
The direction of the force between two charges may be obtained by remembering that:
like forces repel and opposite forces attract
An electric field is:
the electrical force on a stationary positive charge divided by the charge
Electric fields are produced by:
a stationary source charge (q)
A stationary test charge is:
the charge placed in the electric field
Whether the force exerted through the electric field is attractive or repulsive depends on:
whether the stationary test charge and the stationary source charge are opposite or like charges
The equation used to determine the electric field produced by a source charge at a chosen point in space:
E = F/q0 = Kq/r2;
where E is the electric field magnitude, F is the force felt by the test charge q0, k is the electrostatic constant (8.99 X 109), q is the source charge magnitude, and r is the distance between the charges.
E = F/q0 requires:
the presence of the test charge in the electric field
E = kq/r2 does not require:
the presence of a test charge in the electric field
The direction of the electric field vector is given as:
the direction a positive test charge (+q0) would move in the presence of the source charge. If the source charge is positive, the electric field vector radiates outwards. If the source charge is negative, the electric field vector radiates inwards.
A collection of charges in an electric field will exert a net electric field at a point in space that is equal to:
the vector sum of all three of the electric fields
The equation used to determine the total electric field at a chosen point in space:
Etotal = Eq1 + Eq2 + Eq3 + …
The magnitude of the force exerted on a test charge place in an electric field can be calculated using the equation:
F = q0E; where q0 is the charge of the test charge and E is the magnitude of the electric field
Electric potential energy is:
the potential energy related to the relative position of one charge with respect to another charge or to a collection of charges. It is the work necessary to move a test charge from infinity to a point in space in an electric field surrounding a source charge.
The equation used to calculate the electric potential energy between two charges separated in space:
U = kqQ / r
where k = 8.99 X 109, q is one charge, Q is a second charge, and r is the distance between them
