Institution: Hilongos National Vocational School
Subject Title: General Physics 2 (Electricity and Magnetism)
Instructor: Allen I. Dalinog
Academic Year: 2024-2025
Class Description:
Focus on electricity, magnetism, optics, basics of special relativity, atomic and nuclear phenomena.
Utilizes algebra, geometry, trigonometry, graphical analysis, and basic calculus.
Class Schedule: MWF (Monday, Wednesday, Friday)
Class Duration: 1 hour and 20 minutes
Written Works: 25%
Performance Tasks: 45%
Mastery and Quarterly Exam: 30%
Course Requirements:
Scientific Calculator
Physics Notes
Completed Activities
Concept Map Making
Attendance
Lesson:
Electricity and Magnetism
Instructor: Allen I. Dalinog
Year: 2024-2023
University Affiliation: University of Cebu - Main Campus SHS Department
Discuss the concept of electric charge with reference to subatomic particles.
Describe charging by rubbing and induction using diagrams.
Explain the role of electron transfer in electrostatic charging by rubbing.
Question Posed:
What do you think happened?
Electricity:
A form of energy involving the movement of electrons from one point to another.
Electrostatics:
Study of phenomena associated with charged bodies at rest.
Sir William Gilbert:
Coined the term "Electricity" derived from the Greek word "elektron" (amber).
Discovered law of attraction and repulsion between magnets.
Credited for linking electricity with lightning through his famous Kite Experiment.
Contributors:
Alessandro Volta
André-Marie Ampère
Charles Augustin de Coulomb
George Ohm
Graham Bell
Thomas Edison
James Maxwell
Michael Faraday
Notable Figures:
Nicola Tesla
Albert Einstein
Definition:
The buildup of electrical charges on an object.
Occurs through electron transfer from one object to another.
Definition:
Loss of static electricity as charges move off an object.
Types of Discharge:
Within Cloud: Charge transfer between negative base and positive top (intra-cloud).
Cloud-to-Cloud: Discharge between charge centers in clouds.
Typical Cloud-to-Ground Lightning: Discharge between ground and negative charge centers.
Subatomic Particles:
Mass and Charge:
Protons: Mass present, Positive Charge (+)
Neutrons: Mass present, No Charge
Electrons: Negligible mass, Negative Charge (-)
Charge:
Charge symbol: q
SI Unit: Coulomb (C)
Example 1:
To have a charge of 1.0 C, how many electrons must be removed?
Example 2:
Rubbing a comb on hair gives a comb charge of -0.96 C: (a) Identify which material loses and gains electrons.(b) Calculate the number of electrons transferred.
Concept:
Charge is quantized; it must be integral multiples of the fundamental charge (e).
1 C = 6.242 x 10^18 electrons.
Positive Charge:
Object becomes positively charged if it loses electrons.
Neutrality:
All objects start neutral and may become either positively or negatively charged.
Negative Charge:
Object becomes negatively charged if it gains electrons.
Law of Electric Charge:
Like charges repel; unlike charges attract.
Law of Conservation of Charge:
Charges cannot be created or destroyed.
Ways to Charge:
Conduction
Friction
Induction
Definition:
Rubbing two objects causes electrons to transfer ("wiped").
Leads to electrostatic discharge.
Definition:
List of materials ranked by their tendency to gain or lose electrons.
Conductors vs Insulators:
Top items lose electrons (positive); bottom items gain electrons (negative).
Example:
Rubbing dry hands with silk:
Dry hands lose electrons (positively charged).
Silk gains electrons (negatively charged).
Definition:
Transfer of electrons through direct contact.
Example:
Negatively charged cylindrical rod touches a neutral spherical conductor, charging it by conduction.
Function:
Determines if an object is electrically charged.
Components:
Knob, metal rod, metal leaves within a flask.
Indications:
Charged objects cause leaves to repel.
Definition:
Rearrangement of charges in an uncharged object without direct contact with a charged object.
Definition:
Process by which a neutral body becomes polarized through molecular rearrangement.
Concept of Electric Dipole:
A body with a positive charge on one end and a negative charge on the other (dipole).
Observation:
Cords coming from walls made with plastics and metals (insulators and conductors).
Conductors:
Allow easy flow of charge
Examples: Silver, copper, gold, aluminum
Insulators:
Do not allow flow of electrons
Examples: Plastic, rubber, glass, wood, air
Semi-conductors:
Conduct better than insulators but not as well as conductors
Examples: Silicon, germanium
Question:
An object becomes positively charged when which occurs?
A. Loses electrons
B. Gains electrons
C. Loses protons
D. Gains neutrons
Question:
If two charges repel each other, they must be:
E. Positive and neutral
F. Positive and negative
G. Negative and negative
H. Neutral
Question:
Which can be attracted by a positively charged object?
A. Another positively charged object
B. Any object
C. A neutral object
D. No other object
Scenario:
Two rubbed balloons nearing each other; result?
E. Repel each other
F. Attract each other
G. Both become positively charged
H. They pop.
Question:
Using a charged spoon to pick up salt and pepper is an example of charging by:
A. Induction
B. Conduction
C. Friction
D. Static discharge
Question:
Best definition for polarization?
E. Two objects attraction due to charge
F. Neutral object's charges jump to a charged surface due to opposite attraction
G. Neutral object's charges separate due to nearby charge
H. Object gains charge from another object.
Inquiry:
A charged balloon brought near an electroscope without touching demonstrates:
A. Convection
B. Friction
C. Conduction
D. Induction
Example of Friction:
Rubbing a balloon in your hair is an example of charging by:
E. Induction
F. Conduction
G. Friction
H. Grounding
Scenario:
A positively charged rod near a neutral metallic plate induces:
A. Positive charge
B. Negative charge
C. Neutral charge
D. Depending on distance
Question:
A neutral electroscope touched with a negatively charged rod results in:
E. Positive charge
F. Negative charge
G. Remains neutral
H. It depends on contact time.