Chapter 22: Electrostatics Flashcards
Which force binds atoms together to form molecules?
electrical
In an electrically neutral atom the number of protons in the nucleus is equal to the number of
electrons that surround the nucleus.
Strip electrons from an atom and the atom becomes a
positive ion.
The unit of electric charge, the coulomb, is the charge on
a specific large number of electrons.
A transistor is an example of a
semiconductor.
Induction is when
you bring a charged object near another object and cause a movement of charge.
Paper plates don’t heat in a microwave because
paper contains no polar molecules.
The force between two charged particles depends
on the amount of charge on the two particles and their distance from each other.
When a material has no electrical resistance it is
a superconductor.
A volt is defined as
a joule per coulomb.
General term for electrical phenomena
Electricity
The study of electric charge at rest (def)?
Electrostatics
Electric charge is neither created nor destroyed. The total charge before an interaction equals the total charge after (def)?
Conservation of charge
The relationship between electrical force, charge, and distance (def)?
Coulomb’s law
F = k(q1*q2/d^2)
In regard to Coulomb’s law, if the charges are alike in sign, the force is
repulsive.
In regard to Coulomb’s law, if the charges are unlike (opposite), the force is
attractive.
The SI unit of electrical charge?
Coulomb
One coulomb (symbol C) is equal to
the total charge of 6.25 x 10^18 electrons.
Any material having free shared particles that easily flow through it when an electric force acts on them?
Conductor
A material without free charged particles and through which charge does not easily flow?
Insulator
A material with properties that fall between a conductor and an insulator and whose resistance can be affected by adding impurities?
Semiconductor
A material that is a perfect conductor with zero resistance to the flow of electric charge?
Superconductor
Transfer of electric charge between objects by rubbing or simple touching?
Charging by contact
Redistribution of electric charges in and on objects caused by the electrical influence of a charged object close by but not in contact?
Charging by induction
Term applied to an atom or molecule in which the charges are aligned so that one side has a slight excess of positive charge and the other side a slight excess of negative charge?
Electrically polarized
One side of the atom or molecule is induced into becoming more negative or positive than the opposite side.
Defined as electric force per unit charge, it can be considered to be an “aura” surrounding charged objects and is a storehouse of electric energy?
Electric field; Electric field = F/q
About a charged point, the field decreases with distance according to the inverse-square law, like a gravitational field. Between oppositely charged parallel plates, the electric field is uniform.
The energy a charged object possesses by virtue of its location in an electric field?
Electric potential energy
The ______ ________ energy per unit of charge, measured in volts, and often called voltage?
electric potential
Voltage = electric potential energy / charge or V=E/q
An electrical device–in its simplest form, a pair of parallel conducting plates separated by a small distance–that stores electric charge and energy?
Capacitor
Capacitor plates have equal and opposite charges.
According to Coulomb’s law, a pair of particles that are placed twice as far apart will experience forces that are: a) half as strong; b) one-quarter as strong; c) twice as strong; d) four times as strong.
b) one-quarter as strong
Are gravitational forces attractive or reflective?
Gravitational forces are only attractive.
Every atom is composed of
a positively charged nucleus surrounded by negatively charged electrons.
Each of the electrons in any atom has
the same quantity of negative charge and the same mass.
Protons and neutrons compose the
nucleus.
Protons are about 1800 times more massive than ________, but each one carries an amount of positive charge equal to the negative charge of electrons.
electrons
Neutrons have slightly more mass than _______ and have no net charge.
protons
Atoms usually have as many electrons as protons, so the atom has _____ ___ charge.
zero net
When rubbing a comb through your hair, _______ transfer from your hair to the comb.
electrons;
Your hair has a deficiency of electrons (positively charged).
When rubbing a glass rod with silk, electrons transfer from the rod onto the silk and the rod becomes
positively charged.
Metals such as copper and aluminum are considered to be
conductors.
Materials such as rubber and glass are considered to be
insulators.
Materials that fall in the middle range of electrical resistivity between insulators and conductors?
Semiconductors;
They are insulators when they are in their pure state.
They are conductors when they have impurities.
Semiconductors conduct when light shines on it.
Superconductors: Materials acquire zero __________ to the flow of charge.
resistance;
zero resistance aka infinite conductivity
If a charged selenium plate is exposed to a pattern of light, the charge will
leak away only from the areas exposed to light.
Once electric current is established in a superconductor, the electrons flow
indefinitely.
With no electrical resistance, ______ passes through a superconductor without losing energy.
current;
No heat loss occurs when charges flow.
Resistance of a material to the flow of electric charge through it?
Electrical resistance; measured in ohms.
Consider two insulated metal spheres A and B.
They touch each other, so in effect they form a
single uncharged conductor.
When a negatively charged rod is brought near A, electrons in the metal, being free to move,
are repelled as far as possible until their mutual repulsion is big enough to balance the influence of the rod.
Thus, the charge is redistributed.
If the two insulated metal spheres A and B are separated while the rod is still present,
each will be equal and oppositely charged.
An electron buzzing around the atomic nucleus produces an
electron cloud.
The unit of measurement for electric potential?
Volt; V = E / q
1 volt = 1 joule / 1 coulomb
The energy stored in a capacitor comes from
the work required to charge it.
Like charges
repel
Opposite charges
attract
Differences between the charge of an electron versus the charge of a proton:
The charge of an electron is equal in magnitude to the charge of a proton, but opposite in sign.
If you scuff electrons onto your feet while walking across a rug, are you negatively or positively charged?
Negatively charged; You have more electrons after you scuff your feet, so you are negatively charged.
The rug is positively charged.
If a proton at a particular distance from a charged particle is repelled with a given force, by how much will the force decrease when the proton is 3 times farther away from the particle?
It decreases to 1/9 its original value.
If the proton is 5 times farther away it will decrease to 1/25 its original value.
The negative charge at the bottom of the cloud induces a _______ charge at the surface of the ground below.
positive
A charged comb attracts an uncharged piece of paper because the force of attraction for the closer charge is _______ than the force of ________ for the farther charge.
greater; repulsion
the force of attraction for the closer charge is greater than the force of repulsion for the farther charge.
The negatively charged balloon polarizes atoms in the wooden wall and creates a _______ charged surface, so the balloon sticks to the wall.
positively
An H20 molecule is an electric _______.
dipole; meaning the distribution of electric charge is not perfectly even.
Electric charge distributes itself on the surface of all conductors in such a way that the electric field inside the conductors is ______.
zero.
An electric field inside any conductor is zero–so long as no electric charge is flowing.
Increased potential energy or PE is the result of _____ _____.
work input.
When the PE of a mass or charged particle (electric potential) is released it becomes kinetic energy or KE.
Electric potential and voltage mean the same thing (electrical potential energy per unit charge).
