1. Electricity and Magnetism
Physical Science

2. Electrical Force
The force of attraction and repulsion that either pushes or pulls electrical charges

3. Electrical Charges Two Types
Positive Charge (protons)
Negative Charge (electrons)
Overall charge of an object is determined by electrons
Neutral charge means number of protons equals number of electrons

4. Electrical Field Area around a charged particle
Exerts the force that causes other electric charges to be attracted or repelled.

5. Force of Attraction
Object with different charges will move towards each other (attract)
Ex: positive and negative come together

6. Force of Repulsion
Object with like charges will move away (repel) one another
Ex: positive will repel a positive

7. How does a particle become charged?
Gain or lose electrons
Lose electrons = positively charged
Gain electrons = negatively charged

8. Static Electricity
Is the build-up of charge on the surface of an object
Transfer methods:
friction
conduction
induction
Static Discharge
Occurs when a pathway through which charges can move suddenly
Ex: rubbing socks on carpet then touching a doorknob

9. Methods of Charging Charging by Friction
Done by rubbing objects together
Ex: Rubbing a balloon with hair
Balloon gain electrons
Hair loses electrons

10. Methods of Charging Charging by Conduction Charging by touching
Ex: Negatively charged object touches neutrally charge object
Negative object transfer electrons to neutral object
Both objects are negatively charged
Weaker than the original negative charge

11. Method of Charging Charging by Induction
Transfer of charge without contact between materials
Ex: Neutral doorknob and negatively charge hand
When hand is brought close to doorknob, the charges rearrange

13. Electric Current Continuous flow of electric charge
Flows in a single direction
Two Types
Direct Current (DC)
Alternating Current (AC)

14. AC vs DC Alternating Current Direct Current AKA: AC
Flow of electric charge that regularly reverse its direction
Ex: homes & schools
Direct Current
AKA: DC
Charges flow in one direction
Ex: battery-operated devices

15. Current Flow of electrons through a wire
Increase of current means more electrons flowing in the wire
Unit: ampere/amps (A)

16. Resistance Opposition to the flow of charges in a material
Unit: ohm (Ω)

17. Voltage AKA: Potential Difference
Difference in electrical potential energy between two places in an electric field
Unit: volts (V)

18. Conductors vs Insulators
Electrical Conductors
Is a material through which charge can flow easily
Ex: copper, silver, metals
Electrical Insulators
A material which charge cannot flow easily
Ex: Wood, plastic, rubber, air

19. Factors that Affect Resistance
Length of Wire
Long wires = high resistance (longer travel)
Short Wires = low resistance
Thickness of wire (increasing diameter)
Thick wire: low resistance (more electrons flow)
Narrow wire: high resistance

20. Factors that Affect Resistance
Temperature
High temperature: high resistance (electrons collide more)
Low temperatures: low resistance
Composition (make-up)
Conductors: low resistance
Insulators: high resistance
Resistivity: how strongly a material opposes the flow of electric current

22. Ohm’s Law
Voltage in a circuit equals the product of the current and the resistance
Increasing the voltage will increase current
Increasing the resistance will decrease the current

23. Voltage = Current * Resistance
Ohm’s Law Formula
Voltage = Current * Resistance
V=I * R
V=Voltage (V)
I=Current (A)
R=Resistance (Ω)

24. Ohm’s Law Practice
A wire carries 25 amps of current and encounters a resistance of 10 ohms. How much voltage is being supplied to the wire?
A 300-V battery is attached to a wire that has 100-A of current. What is the resistance of the wire?

25. Electrical Power
The rate at which electrical energy is converted to another form of energy
Ex: hair driers turn electrical energy into thermal energy

26. Electrical Power Formula
Electrical Power = Current * Voltage
P = I * V
P= electrical power (W)
I= current (A)
V= voltage (V)

27. Electrical Power Practice
How much power is there when a 20-A current in a light bulb has a voltage of 10-V?
A 90-W light bulb has a current of 45-A. What is the voltage in the system?

29. Circuit A complete path through which charge can flow
Uses circuit diagrams to understand the path
Symbols represents parts of a circuits
Four types
Open
Closed
Series
Parallel

30. Circuit Parts and their Symbols
Light Bulb (Resistance)
Switch
Battery/Power Source
WIRE
Current Flow

31. Open vs Closed Circuits
Open Circuits
A circuit in which a switch is involved
Switches can stop the flow of electrons
Closed Circuits
No switch is in the circuit
Electrons flow automatically

32. Series Circuits
Charge has only one, single path through which it can flow
If one light bulb goes out, all bulbs go out
More bulbs on the circuit means more resistance, decreasing current and bulbs are dimmer

33. Parallel Circuit
Circuit with multiple pathways that electrons can flow
If a light bulb goes out in a branch, the other light bulbs will stay on
Voltage is the same in each branch, so current flows through the branches with lower resistance

34. Practice

35. Drawing Diagrams Practice
A closed, parallel circuit with three branches. One bulb on each branch.
An open, series circuit with 4 light bulbs.

36. Drawing Diagrams Practice
An open, parallel circuit that has three branches. On the first and third branch has two light bulbs. The second branch has one light bulb. Lastly, there is a light bulb on the main wire.

38. Magnetic Force
The force of attraction or repulsion between two objects

39. Magnetic Poles North Pole & South Pole
Magnetic forces goes from the North Pole to the South Pole
Forces are strongest at the poles

40. Magnetic Field
Surrounds a magnet that exerts a force on other magnet and objects made of magnetic materials

41. Attraction & Repulsion
Opposite poles attract or come together
North & South Poles
Repulsion
Like poles repel or push away
North Pole and North Pole
South Pole and South Pole

42. Breaking a Magnet
If you split a magnet into two equal parts, you form two smaller and equal magnets

43. Magnetic Domains
A group of atoms with aligned magnetic poles in the same direction
This can be used to make materials magnets.

44. Magnetic Induction
The process by which materials are made into magnets
Done by aligning magnetic poles/domains
How?
Stroke materials in the same direction with a strong magnet

45. Electromagnetic Is a solenoid with a ferromagnetic core (iron nail)
Materials needed:
Nail
Wire
Battery

46. Solenoid
A coil of current carrying wire that produces a magnetic field
The loops of wire with electricity
Acts like a bar magnet

47. Strength of Electromagnetic
Increasing current will increase the strength
More turns of the wire will increase the strength
Use an iron core

48. Practical Uses of Electromagnetics
Electric Motors
Created by Oersted
Uses electromagnetic to turn an axis
Converts electrical energy into mechanical energy

49. Practical Uses of Electromagnetics
Electric Generators
Created by Faraday
Uses electromagnetic induction
Changing magnetic field to create current
Converts mechanical energy to electrical energy

50. Practical Uses of Electromagnetics
Transformers
A device that increases or decreases voltage of an alternating current
Has primary and secondary coils
Two Types
Step-up: Increase voltage
Step-down: Decrease voltage
Ex: telephones, electricity supply industries

51. Practical Uses of Electromagnetics
Speakers
Solenoid placed around one pole of a permanent magnet
Current changes direction to increase or decrease sound