1. Electric fields.

6. Q 1 Q 2 r Notice must be paid to the charges of the bodies, the charges may not be the same magnitude or have the same polarity (+ve or –ve)

13. Radial fields (draw in the radial field lines) Q+ Q-

30. Can be used to describe the field – direction is the direction of the force on a positive charge Can be used to describe the field – direction is the direction of the force on a mass Field lines Infinite, decreases with distance but theoretically never reaches zero. Infinite, decreases with distance but theoretically never reaches zero. Range of field Contact not needed, acts at distance Contact not needed, acts at distance For the force to act Electrical Gravitational

31. Can be used to describe work done in moving charges: (inverse law) Can be used to describe work done in moving masses: (inverse law) Potential Given by Coulomb’s law: Given by Newton’s law of universal gravitation: Force between 2 objects. Force on a unit charge: Force on a unit mass: Field strength

32. Kinetic energy Field strength is (-ve of) potential gradient. Field strength is (-ve of) potential gradient. Relationship between potential and field strength. Electrical PE: GPE: Potential energy

33. Differences Comparative sizes Shielding Effect Produced by and acts on charges Produced by and acts on masses Origin