Fields

• Field lines show direction of force on a mass or POSTIVE charge
• Force between two objects is proportional to the product of their masses/charges and inversely proportional to the square of their separation (r)
• Potential (V) is the work required to move unit mass/charge from infinity to that point
• As object gets closer to planet or charged particle, potential gets more negative as we take infinity or between unlike charges as 0
• Potential is scalar so direction is irrelevant
• equipotentials are lines perpendicular to field lines. They show certain potentials, the closer together these are the stronger the field.
• Change in potential x mass (or charge) will give change in potential energy or work done
• r is always distance from centre of mass or charge
• Can find change in potential from V-r graphs by finding points along the curved line
• Gradient (tangent) of potential - r graph gives the field strength
• When there is no potential difference between two point masses/ charges. V1=V2