Electric Fields Flashcards
When calculating the force between two particles, what can air be treated as?
A Vaccum
For a charged sphere the charge can be assumed to be what part of the sphere?
The Centre
Which is stronger?
Gravitational force of subatomic particles or the electrostatic force
Electrostatic force
Electric Field lines always go from ____________ to ___________
Positive charge to a negative charge
What is electric fields strength
The force per unit charge on a small positive test charge acting at a point in an electric field
What is the trajectory of a particle entering perpendicularly to a uniform field
Parabolic
How is electric potential related to electric field strength
E = Chnage in V / Change in R
The change in electric potential in respect to radius length
A +4 nc and a +6 nc charges have a distance of 50x
Draw the Corresponding electric field
1) A = 4/6B & A+B = 50x
2) 50x = 10/6B
3) B = 30X —-> A = 20x
4) A needs to have less field lines due to a smaller magnitude of charge
What do electric field lines show?
.the path of a free positive test charge would follow in that electric field
Name an example that produces a:
.Uniform electric field
.Radial Electric field
.Parallel plates
.Point charges
Write out the derivation for E = V/D
VM^-1
only in parallel electric field
What is electric potential
Work done per unit charge on a small positive test charge when it is moved from 1 point in a field to infinity
What is Coulomb’s Law
What does negative and positive values signify?
For 2 point charges the force between them is proportional to the product if the magnitude of the charges & inversely proportional to the square of the distances between them
F = Negative then its an attraction
F = Positive then its a repulsion
Name the conditions for coulomb’s law
1) Charges must have a spherically symmetrical charge distribution
2) Charges must not overlap —> has to be 2 distinct point charges
3) Charges must be stationary with respect to one another
How do you derive the field strength for a radial field equation
Coulomb’s law & E = F/q
where q is equal to the test charge
How do you derive the electric potential equation
Coulomb’s law & Wd = Vq
Explain the difference in how insulation and conductive metals distribute charge
Insulating metals —> No free electrons , easy to gain and loose charge on the metals surface
Conductive metals —> Free electrons move throughout the metal, only can be charged by isolating it from the earth, as electrons flow between the metal and the earth otherwise
Even if a point between electric fields has net 0 electric field strength between 2 alike charges
Why does it still take/cost energy to move a proton from that point to infinity
Electric potential and field strength are not the same
electric potential at infinity is zero
There still is a positive electric potential at that point so Work must be done on the proton
Name a difference between an Electric and Gravitational field
Grav field only shows attraction
Electric field can show attraction and repulsion
1) Terminal Velocity means there is no resultant force acting on the object
2) PD increases increases the magnitude of charge accumulating on the positive plate
3)This creates an electrostatic force acting in a direction which opposes the motion
4) Electrostatic forces increase when pd increases
5) Resultant force acts upwards causing the drop to accelerate in the opposite direction to motion
6) so negatively charged drop speed decreases until stationary.
7) Drop remains stationary when Weight = electrostatic force from positive plate.
What is meant by an electric field
region where a charged particle experiences a force
