Electric Fields Flashcards
Coulomb’s law equation
F=Q1Q2/4piEor^2
F is force (N)
Q is change of object 1 and 2 (C)
Eo is permittivity of free space:8.85*10^-12m^-3kg^-1s^4A^2
r is distance between object 1 and 2 (m)
When does Coulomb’s law hold true?
When we assume all charge at a single point
For Coulomb’s law what charges can Q be if F is positive?
++ or - -
For Coulomb’s law what charges can Q be if F is negative?
-+ or +-
How to describe motion of charge if there is overall unbalanced force is toward x
Accelerating towards x
What is the charge of the particle we use in field diagrams?
Positive
Left hand rule is used for…..
Positive Charge
Right hand rule is used for….
Negative charge
Equation for force with charge and electric field.
F = QE
F is Force (N)
Q is charge (C)
E is electric field strength (NC^-1)
Electric field strength definition
Force acting per unit positive charge in an electric field
Electric field strength equation
E = Q/4piEor^2
E is electric field strength (NC^-1)
Q is charge of object (C)
Eo is permittivity of free space -8.85*10^-12
r is radius (m)
Electric potential definition
The work done by external forces in bringing a unit positive charge (1C) from infinity to that point.
Electric potential equation
V = Q/4piEor
V is electric potential (V)
Q is charge of object (C)
Eo is permittivity of free space: 8.85*10^-12
r is radius (m)
How to find distance if closest approach
Ek=Ep field(QV)
Work done in electric field equation
Ew = VQ
Ew is work done (J)
V is electric potential (V)
Q is charge (C)
What type of field is an electric field?
Conservative field
Conservative field definition
Work done in moving an object between two points in the field is independent of the path taken.
Electrical potential and distance equation
V=Ed
Where V is electrical potential (V)
E is electric field strength (NC^-1)
And d is distance (m)
Equation for acceleration of charged particles in field
a =QE/m
Where a is acceleration (ms^-2)
Q is charge of particle (C)
E is electric field strength (NC^-1)
m is mass of particle (kg)
When talking about motion of charged particle of fields what should always be referred to
Balanced / unbalanced forces
Combining of electrical potential equation from 2 charges
V(total) = Q1/4piEor + Q2/4piEor
Don’t ignore charges potential can be positive or negative.
When explaining parabolic curve of electron in cathode ray tube, what points should be hit?
Unbalanced force in vertical direction, vertical acceleration.
Balanced force in horizontal direction, constant horizontal velocity.
Can electric potential be -
Yes
Combining of electric field strength equation from 2 charges
E(total) = Q1/4piEor^2 + Q2/4piEor^2
Don’t ignore charges
