Dipole Flashcards
What is an electric field defined by?
1) electric field strength
2) electric potential
What is the symbol for the “electric field strength”?
E with an arrow on top
What is the equation for calculating the electric field strength?
E (arrow) = F (arrow) / q
E (arrow)- electric field strength
F (arrow)- net electric force
q- magnitude (of the test charge)
What do fields do? What does that cause?
they superimpose each other, forming a single net field.
What does the vector specify? What is a vector?
The vector specifies the magnitude of the net field at any point.
It is the vector sum of the values of fields due to each individual source.
What is Coulombs law? What does it explain?
Coulomb’s law describes the strength of the electrostatic force (attraction or repulsion) between two charged objects.
What is the Coulombs law equation?
E= k*q / Er^2
E- electric field
k- permitivity constant
q- charge
E-
r- radius
What is the symbol for potential?
φ
o with a vertical line going across it.
What is the electric potential?
The amount of work needed to move a unit charge from a low potential region to a high potential region against an electric field.
What is the equation for electric potential?
φ=W/q
φ- electric potential
W- work
q- charge
What does q stand for?
charge
What does W stand for
work
What is the equation for the potential φ of charge q?
φ = kq / (er)
φ- potential
k- constant
q- charge
e- emittance
r- radius
How to express the electric field strength as a ratio in regards to potential difference?
E (arrow) = -dφ / dr
E (arrow) = - gradient φ
E (arrow) - electric field strength
φ - potential
What does the minus sign represent in the ratio of the gradient of potential to the electric field strength?
the field strength direction coincides with a decrease in potential.
field strength and potential are inversely correlated.
NOTE: the greater the field strength (closer together), the smaller the electric potential (less work had to be done to carry the “ball” up).
What does a dipole consist of?
- two charges
- equal magnitude
- opposite charge
- held at a fixed distance
- make up a single unit
What is magnitude?
The absolute or relative direction or size in which an object moves in the sense of motion.
What constitutes to the dipole moment?
the product of the charges or their seperation.
What is the equation for the dipole moment?
p (arrow) = (q*1) (arrow)
p- vector quantity (pointing fro the negative charge to the positive charge)
What are the units of the dipole moment?
C×m
Why do some molecules have a dipole moment?
Because they exhibit a charge seperation.
Why does water have an electric dipole moment?
Because the electrons in a water molecule spend most of their time in the proximity of oxygen.
Why does a molecule develop a dipole moment?
Random fluctuations in the configuration of a molecule lead to charge separation causing a molecule to develop a dipole moment.
What does a dipole moment give rise to? What is the further effect?
Dipole moments give rise to electric fields which cause charge separation in nearby molecules, giving them a dipole moment as well.
