Electric & gravitational fields

• magnitude of the electric field strength in a uniform field is E=V/d
• all charged particles generate an electric field that exerts a force on charged particles around it
• Coulombs Law - the electrostatic force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of their separation
• what is the electrostatic forces between two point charges directly proportional to?


  The product of their charges
• What is the electrostatic force between 2 charges inversely proportional to?


  The square of their seperation
• Electric potential difference = work done per unit charge
• Permittivity of free space - e0
• Permittivity is a measure of the resistance of a material to creating an electric field within it
• Electric force is attractive when it is negative and Q1 and Q2 are opposite charges
• Electric force is repulsive when it is positive and ions are attracted to each other.
• Coulombs Constant (k) is 8.99 x 10^9
• The equation for Coulomb's Law is F= kQ1Q2/r^2
• In a uniform electric field the electric field strength is constant at all points - shown by field lines being equally spaced
• In a radial electric field the electric field strength ε is maximum at the centre of the field and decreases outwards
• Field lengths go from positive to negative
• Electric field strength is the force per unit charge experienced by 1 coulomb of charge in a field
• Electric field strength is measured in NC^-1
• The greater the voltage between two plates with a uniform electric field the stronger the field
• The greater the seperation between 2 plates with an electric field the weaker the field
• Electric field strength = F/Q = V/d
• A charged particle in an electric field will experience a force on it that causes it to move
• if a charged article in a uniform electric field is stationary it will move parallel to the electric field lines
• If a charges particle is in motion through a uniform electric field it will travel in a parabolic trajectory. If it is positive it will curve towards the negative plate
• A charged particle in an electric field will experience a constant force that is always in the same direction
• Amount of deflection influences when the particle hits the plate and the shape of its curve
• What does less deflection mean for a particle in an electric field.


  The particle will hit the plate later, the path has a smaller curve
• Amount of deflection increases as mass decrease, charge increases, speed decreases
• Electric force is proportional to charge, F =EQ
• The strength of an electric field due to a point charge decreases with the square of the distance - inverse square law
• In a radial electric field electric field strength is not constant
• Electric potential of a point charge is the work done per unit charge in moving the point charge from infinity to that point
• The electric potential at a point depend on the magnitude of the point charge and the distance between the charge and the point
• The potential gradient is defined as the change of potential per unit charge of distance (how much the potential changes per m) Δv/Δr
• For a uniform field the gradient of a V-R graph is a constant (the potential gradient)
• For a uniform field the electric field strength = -v/r
• When a charge moved through an electric field work must be done to it - W=qV
• Equipotential lines have the same electric potential and Andre perpendicular to the electric field lines
• A radial field is made up of lines which follow the radius of a circle
• A uniform field is made up of lines whicha re a uniform distance apart
• How does Coulomb's law describe the relationship between force, charge, and distance?


  Force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.