Electric Fields Flashcards
Define an electric field and how does it differ to a magnetic field?
A region in space in which a charge particle will experience a non-contact force.
(For magnetic field the charge must be moving)
Give two units for electric field strength.
- N.C^-1
- V.m^-1
State an equations for electric field strength
- E = F/Q
- E= kQ / r^2 (Where k is 8.99*10^9 and r is the distance from the charge centre to the point)
When will a point charge no longer have a concentric, circular equipotentials
In the presence of another field (the field lines will not cross)
What is the name give to two or more fields interacting with each other
A compound field
State Coulombs Law
F = (k.Q.q) / r^2
where k = 1/(4.Pi.EpsilonNort)
What is a limitation of Coulombs Law
It is only applicable to radial charges
What is a radial charge
A charge which produces an electric field which decreases with intensity as you move away from it.
e.g. Proton
What assumption can be made about spherical charges?
All the charge is concentrated from a single point in the centre
Define a point charge
All the charge is concentrated from a single point in the centre
State the equation for Electric potential energy gained
BY A SINGLE CHARGE, NOT THE WHOLE SYSTEM
V = kQ/r
where k = 8.99x10^9 or 1/(4.Pi.EpislonNort)
State the equation for work done to move a charged particle a distance into an electric field
Q.(Delta)V
where V is the electric potential energy
What is the relationship between force and separation between two charges
Coulomb’s Law!! => Inversely proportional to the square of separation (inverse square) and directly proportinal to the product of the charges.
Define electric potential.
Amount of work needed per unit charge to go from point a to point b
Is electric potential energy a vector or scalar quantity?
Scalar, although can be negative (Moving from positive potential to negative potential is a negative change in electric potential energy)
What is meant by the term equipotential?
An imaginary loop surrounding a field where the electric potential is the same.
What does it mean if work done moving a charge into a field is positive?
Work is done AGAINST the field. Vice versa…
What is the relationship between electric potential and distance form the charge.
Inversely proportional.
What feature of a Force / Distance graph gives the change in electric potential?
Area under graph between specified points.
What feature of an electric potential / distance graph gives the electric field strength at a point d.
The gradient of the curve at d.
How do you calculate electric potentials of a charge affected by multiple charges?
Sum the potentials
How are electric field vectors orientated relative to equipotentials?
Orthogonally (Perpendicular) - In the direction of decreasing field strength.
What equation can be used to calculate electric field strength of a uniform field.
E = (Delta)V / (Delta)r
where V is the electric potential and r is the separation between the two potentials
Define a uniform field.
Parallel, evenly spaced field lines and evenly spaced equipotentials.
State the equation to calculate TOTAL Electric potential energy gained.
E(Total) = K.Q.q / r
