Physics #5 Flashcards
electrostatics
the study of stationary charges and the forces that are created by and which act upon these charges
gravity is ____ an attractive force
always
is static charge buildup/static electricity more significant in drier air or humid air?
drier air because the lower humidity makes it easier for charge to become and remain separated
what is the charge of an electron or a proton?
1 Coloumb
1.6x10^-19
like mass and energy, electric charge is governed by a _______. This law states that charge can neither be created nor destroyed.
law of conservation of charge
insulator
will not easily distribute a charge over its surface and will not transfer that charge to another neutral object very well.
why are insulators poor conductors?
on a molecular level, the electrons of insulators tend to be closely linked with their respective nuclei.
conductor
when given a charge, the charges will distribute approximately evenly upon the surface of the conductor.
why are conductors so good at transferring charge?
they are considered as positive nuclei surrounded by a sea of electrons.
where do electric field lines point?
toward the negative charge.
how do electric fields make their presence known?
by exerting forces on other charges that move into the space of the field.
what is small q vs. big Q
Q: source charge
q: test charge
Is electric field a vector or scalar quantity?
vector
by convention, the direction of the electric field vector is given as the direction that a____ test charge would move in the presence of the source charge
positive
what do the electric field lines look like for a neutral point in space?
there are none.
does the source charge or the point charge create the electric field?
the source charge
what is the sign on potential energy if the charges are like charges?
positive
what is the sign on potential energy if the sizes are not like charges
negative
what are q1 and q1 in the electrostatic force equation?
magnitude of charges
How is electrical potential energy defined?
for a charge at a point in space in an electric field it is the amount of work necessary to bring the charge from infinitely far away to that point.
A smaller (more negative) potential energy represents _____ stability
more
where do two like charges have the greatest stability?
furthest apart
where do two unlike charges have the greatest stability?
closest to each other
is electric potential a scalar quantity or vector quantity?
scalar
for a collection of charges, the total electric potential at a point in space is ______
the scalar sum of the electric potential due to each charge
what is the name for the potential difference between two points in space?
voltage
the ____ end of a battery is the high potential end while the _____ end of a battery is the low potential end
plus
minus
Positive charges will spontaneously move in the direction that ______ their electric potential (_____ voltage), whereas negative charges will spontaneously move in the direction that______ their electric potential (___ voltage). In both cases, electrical potential energy is ___.
decreases, negative
increases, positive
decreasing
the potential difference between any two points on an equipotential line is ____
0
in electrostatics, work depends only on the _____ and not the path taken
potential difference
how do chemists and physicists indicate dipoles differently?
physicists indicate the dipole in the opposite manner of chemists.
in a dipole, we are assuming the charges on either end are ______
equal and opposite.
what does torque on a dipole moment do?
it causes the dipole moment to reorient itself so the dipole moment aligns with the electric field.
any moving charge creates a _____
magnetic field
what is the SI unit for magnetic field strength
tesla (N)(s)/(m)(C)
diamagnetic materials
made of atoms with no unpaired electrons and that have no net magnetic field. Slightly repelled by a magnet.
paramagnetic materials
unpaired electrons so do have a net magnetic dipole moment but no net magnetic field.
weakly magnetized in the presence of an external magnetic field, aligning the magnetic dipoles of the material with the external field.
ferromagnetic materials
unpaired electrons so do have a net magnetic dipole moment but no net magnetic field.
strongly magnetized in the presence of an external magnetic field, aligning the magnetic dipoles of the material with the external field.
the sum of electrostatic and magnetic forces is known as the ____ force
Lorentz
how to do RHR for current carrying wires
thumb in direction of current and wrap fingers
how to do RHR for magnetic force
thumb in direction of velocity
fingers in direction of magnetic field lines
palm is direction of force vector for positive charge
back of hand is direction of force vector for negative charge
at the perpendicular bisector of a dipole, the electric potential is 0 because ______
electric potentials are additive.
