Chapter 22- Electric fields

• An electric frield is created by charged objects
• The electric field strength is defined as the force experienced per unit positive charge
• Electric field strength is a vector quantity
• Electric field lines move away from a positive charge
• Closer electric field lines represent greater electric field strength
• Coulombs law states that any two point charges exert an electrostatic force on each other that is directly proportional to the product of their charges and inversely proportional to the square of the distance between them
• Coulombs law can be investigated using a scale to record the force
• Gravitational fields are created by mass whereas electric fields are created by charge
• Gravitational fields are always attractive whereas electric fields are attractive for negative charges and repulsive for positive charges
• Gravitational field strength is the force per unit mass whereas electric field strength is the force per unit positive charge
• Both electrical and gravitational fields produce radial fields
• To determine the electric field strength between two parallel plates, the equation E = V/d can be used
• The capacitance of a parallel plate capacitor depends on the separation between the plates and the area of overlap between the plates giving the equation C=ε0 A/ d
• An electron in a parallel electric field will travel towards the positively charged plate, in the opposite direction the to electric field and will therefore experience a constant electrostatic force and so has a constant acceleration
• When a charged particle is moving at right angles to an electric field will have the same motion as an object travelling in a gravitational field with a vertical acceleration also
• The area under a force separation graph is equal to work done, elastic potential energy
• Electric potential is defined as the work done per unit charge to bring a positive charge from infinity to that point
• Electric potential difference is the work done per unit charge between two points around the charged particle
• An equipotential line is a line or a surface along which the electric potential is the same