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Module 6 - Chapter 22 - Electric fields I - Coggle Diagram
Module 6 - Chapter 22 - Electric fields I
Electric Fields
Field - Region where electrostatic forces are exerted on objects due to their properties, at a distance
Detecting
Use a thin strip of gol foil attatched to the bottom of an insulator
You havea positively charged ball
Gold foil is given a constant positive charge when it touches the ball
Ball experiences an electrostatic force when close to the ball, and the force is smalled that further away the foil is from the ball
Electric field strength
Force per unit positive charge acting on an object in a field
Unit for electri field is
Vector quantity - direction of the electric field at a point is the direction in whcih a positive charge would move when place at that point
Direction of an electric field is thee direction of the force exterted on a positive charge
You can swap the direction of force acting on a neatively charge particle to find the field direction
Electric field patterns
Arrow shows direction of the field
Lines are always at right angles to the surface of a conductor
Equally spaced parallel field lines represent a uniform field - field strength is the same everywhere
Closer field lines represents greater electric field strength
Uniform sphere
Field is radial in both cases and decreases with distance from centre
You can model the uniformly charged sphere as a point charge at its centre
Lines point outward from a positive charge and inwards towards a negative charge
Lines meet the surface of a conductor at right angles
Coulomb's law
Any two point charges exert an electrostatic force on eacother other that is directly proportional to the product of their charges and inversely proportional to the square of the distance between them
Force experiencs by each point charge is F
According to Newton's third law, the points experience equal but opposite forces on eachother
Investigating
Apply Coulomb's law to large uniformly charged spheres
take r as the separation between the centres of the two spheres
You cna charge balls by touching them with positively charged electrodes
Lowering on of the charged spheres will produce a larger reading on the mass balance
Radial fields
E at a distance r from the cntre equals the force experiences by a postive charge (q) divided by the charge on q
E is directly proportional to the charge Q and obeys an inverse square law with distance r
Graph of E against 1/r^2
