AP Physics 1: NGSS - Electrostatics, Electromagnetism

Electrostatic Charge

Deficiency or excess in electrons on ungrounded or insulating surfaces

Charge of an electron

1.6 * 10^-19 C

Neutral objects

attract both positive and negative objects

Coloumb's Law

F electrostatic = Kq1q2 / r^2

Coloumbs constant (k)

9 * 10^9 Nm^2 / C^2

Charging by friction electrons are transferred from one material to another when they RUB/SLIDE against each other

Result: Differently charged objects - Ex. balloon and hair

Charging by contact

Charge by direct contact, will have same charge in end - Ex conducting spheres

Charging by induction

No direct contact, attraction of opposite charges and involving grounding to remove the charge, Different charges in the end

If two objects attract, and one is charged, was the other charged?

No, the other object could have been polarized

Electric potential energy

The energy a charged object possesses due to it's location in an electric field.

Electric potential difference Aka Voltage

amount of energy per unit of charge in volts (J/C)

V = E / q

Voltage = electric potential energy (J) / charge (C)

Current

Amount of charge that flows per unit of time

Current Formula

I = q (c) / t (sec)

Resistance

Tendency to oppose the current

Equation for resistance

R = pL/A

Conventional current flow

From + to -

17. Electron flow (reality)

From - to +

18. DC

Direct current; from battery, one direction

19. AC

Alternating current; from outlets(generators), alternating direction

20. Are electrons supplied to your home?

No, only energy is supplied to your home. The electrons vibrate back and forth between your home and power lines

21. Fuses

Has a thin strip of metal that will melt if to much current flows through. -needs to be replaced once overloaded. -protects circuits from overheating

Breakers

Has an internal switch that is tripped upon unsafe surge of electricity -simply reset and re-used -protects circuits from overheating

23. Why do we use parallel circuits?

Because in series, if one component of the circuit breaks, the entire circuit will not function. In parallel, each component relies on itself and will not affect the other

24. Cause of resistance to the

Mobile charge carries(free-moving electrons) collide with atoms ofthe resistor

25. Electric fields

Go/supply from + to -

26. Farraday's Cage Experiment

where Farraday lined a room in metal foil and bombarded it with electricity. The room's inside stayed devoid of electricity. Realization: Field within a CONDUCTOR cancels out external fields, making the inside have zero charge

27. Generally, magnetism is caused by

moving charges

28. In an atom, magnetism is caused by

spin of electrons

29. In earth, magnetism is caused by

motion of liquid in the outer core

30. Feromagnetics

Materials that have domain - Random directions in divisions -> All attracted (strong)

31. Paramagnetics

Weak attraction to one pole - Random directions -> Mostly attracted (weak)

32. Diamagnetics

Repel both poles - Random directions -> All repel (strong)

33. Energy is a result of

magnet motion

34. Cutting a magnet in half results in a

full magnetic dipole

35. Oersted's experiment

Oersted set up a compass through a wire carrying current: Showed that moving electrons create a magnetic field

36. In electromagnetics, opposites ___ and alike ___

repel, attract (opposite of other electro logic)

37. Farraday's Law

Generator's voltage is directly proportional to: - number of loops, - speed/rate at which magnetic field is changing (flux)

38. More loops =

Greater magnitude

39. Farraday's Law in equation

v1/v2 = n1/n2 (n = num loops)

40. Transformers

A device that transfers electric current from one circuit to another, by means of electromagnetic induction and usually to change voltage.

41. Electromagnetic Induction

Change in magnetic field creates voltage/current/change in electric field

42. Motors

Electric -> Mechanical energy, Ex: Electric car motor

43. Generators

Mechanical -> Electric energy, Ex: power plants

44. Wave

An energy disturbance that travels through space

45. Amplitude

Maximum displacement from equilibrium

46. Wavelength

Distance between 2 consecutive points at the same phase

47. Frequency

Number of cycles per second

48. Speed only changes when

the medium changes

49. Transverse waves

Perpendicular (vertical) waves - Ex: literally all waves

50. Longitudinal waves

Paralell (horizontal) waves, moves parallel to wave propagation - Ex: Slinky

51. To propagate, waves require

a medium

52. Reflection

The bouncing back of a wave when it hits a surface through which it cannot pass - ex: mirror

53. Refraction

The bending of a wave as it passes at an angle from one medium to another, ex: object in a water cup

54. Interference

The combination of two or more waves that results in a single wave

55. Standing wave

Interference of original and reflected waves

56. Speed can only be changed through

medium