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# Unit 4: Physics
**SCIENCE — WORD WALL**
## SCIENCE — WORD WALL
|Term |Definition|
|:----|:---------|
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| Electrostatic series | a list of materials arranged in order of their tendency to gain electrons|
| Charging by conduction | charging an object by contact with a charged object|
| Grounding | connecting an object to a large body, like Earth, that is capable of effectively removing an electric charge that the object might have|
| Conductor | a material that lets electrons move easily through it|
| Insulator | a material that does not easily allow the movement of electrons through it|
| Conductor | a material that lets electrons move **easily** through it|
| Insulator | a material that **does not** easily allow the movement of electrons through it|
| Charging by induction | charging a neutral object by bringing another charged object close to, but not touching, the neutral object|
| Electric discharge | the rapid transfer of electric charge from one object to another|
| Lightning | a bolt of electricity from sky :D|
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| Resistor |a device that reduces the flow of electric current|
| Ohm’s law |the straight line relationship between voltage and current; `R = V/I`|
## Static Electricity
## Static Charges
- `Static Charges`: An unequal number of individual electric charges on the surface of an object.
- Basically, the charges are **nearly fixed** on the **surface** of an object.
- `Net Charge`: The total electrical charge of an object, in other words, the difference between the protons and electrons.
- An object is:
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- Charge is basically the difference between the amount of protons and electrons, the greater the difference, the greater the charge.
- A greater charge between objects is determined by the amount of difference between the protons and electrons in each of the objects. The one with more difference has a greater charge.
## Charging By Friction
- When 2 objects of different materials rub against one another, the electrons moves between the objects, one loses electrons and the other gains electrons.
- The object that gains electrons becomes negatively charged, and the other becomes positevely charged.
## Triboelectric Series / Electrostatic Series
- Different materials have different abilities to hold onto electrons
- `Triboelectric Series`: A list of material that is arranged according to their ability to hold on to electrons.
### Table Of Tribolecetric Series Of Common Materials
<img src="https://files.catbox.moe/i7ez1v.png" width="500">
## Law Of Electric Charges
- `Electric Charges`: A charged object has the ability to exert a force (ability to exert energy)
- This charges can either be **Attractive force** (pulling together) or **repulsive force** (pushing apart).
1. Objects that have like charges **REPEL** each other.
2. Objects that have opposite charges **ATTRACT** each other.
3. A neutral object is **always attracted** to a charged object.
## Charging Statics
- There are **3 methods** in charging a neutral object
1. Charging by Fricion
2. Charging by Contact
3. charging by induction
- There are **3 methods** in discharging a charged object
1. Ground
2. Discharge
3. Time
### Charging By Friction
- When 2 objects of different materials rub against one another, the electrons moves between the objects, one loses electrons and the other gains electrons.
- The object that gains electrons becomes negatively charged, and the other becomes positevely charged.
### Charging By Contact
- When two objects of different electric charge touch each other, they will **balance** the charge, by transferring electrons from one object to the other.
- There are alot of different scenarios.
1. When a **postive** touches a **neutral** object.
- electrons are transferred from the **netural** object to the **postive** object.
2. When a **negative** touches a **neutral** object.
- electrons are transferred from the **negative** object to the **neutral** object.
3. When a **negative** touches a **negative** object.
- The object with more **negative charge** (more electrons) will transfer some of its electrons to the weaker charged object.
4. When a **positive** touches a **positive** object.
- The object with less **positive charge** (more electrons) will share some of its electrons to the object with more protons.
5. When a **positive** touches a **negative** object.
- The **negative charged** (more electrons) object will transfer its electron to the **positively charged** (less electrons) object.
#### Summary
1. When an **positively charged** object touches a **neutral** object, the electrons in the **neutral** object will more to the **positively charged** object.
2. When an **negatively charged** object touches a **netural** object, the electrons in the **negatively charged** object will more to the the **neutral object**.
3. When 2 **charged** objects touch, the one with **more electrons** will move its electrons to the one with the **lower** charge.
### Charging By Induction
- Charging a neutral object by bringing another charged object close by, but not touching the neutral object.
- There are 2 types of this, one is temporary and one is more permanent.
- `Grounding`: When a object is really big like the Earth, it will remove the charge on the object and return it to neutral. The reason is due to the Earth's size, so it can lose and gain electrons **without any effect**.
### 1. Charging by Induction temporarily: Induced Charged Separation
- The electrons in the charged object get attracted by the positive charges in the netural object, thus pushing away the electrons in the neutral object, in essence, its **charge seperation**.
- The like charges will be repelled from the induction point, and the opposite charges will be attracted to the induction point.
- After the charged object is removed, the object will reutrn neutral. This is why this is a temporary way of charging an object.
### 2. Charging by Induction Permanently: Induced Charge Separation + Ground
- Basically, after being touched by a charged object, the neutral object will have a temporary charge, then the ground removves some of the electrons in the object, and afterwards, the object stays positive.
- If the object is removed before the ground, it goes by to neutral, the ground must be **removed first** inorder to permantely charge the object.
## Conductors and Insulators
- A conductor is a type of material that allows electrons to flow easily throught it.
- A insulator is a type of material the has high resistance agains the flow of electrons throught it.
|Example|Type|
|:------|:---|
|Lightning Rod|Conductor|
|Copper|Conductor|
|Silver|Conductor|
|Rubber|Insulator|
|Plastic|Insulator|
## How Lightning Works
- In the cloud, it acts as a guant electrical generator.
- Water droplets rise up and freezea and fall back, they are now either postive or negatively charged.
- The negative charges go to the cloud and the postiive charges move to the top.
- When the charges reunite, lightning will strike.
## Dangers / Applications of Electrostatics
- **Dangers**:
- Any sparks are small inginitions in places such as gas stations or oil refineries can cause fires and expolsions.
- **Applications**
- remove pollutants
- coat / paint surfaces
- fabric softener sheets
## Static & Current Electricity
- `Static electricity`: an imblanace of electric charge on the **surface** of an object. Generally, it happens in **insulators**.
- Example: Static in hair, charging by conduction...
- `Current electricity`: The controlled **flow** of electrons through a conductor. Generally, it happens in **conductors**.
- Example: Cell phone, computer, washing machine...
### Types of Currents
- There are 2 types of current electricity, **Direct current** and **Alternating Currnet** (ACDC).
### 1. Direct Current
- The electricity flow in which the electrons flow in **one direction** only.
- Example: any device that use battery such as cell phone, IPod, alarm clock, camera, etc.
### 2. Alternating Current
- The electricity flow in which the electrons **repeatedly reverse** flow direction.
- Example: Any device that use electric power outlet such as television, printer, XBOX, etc.
## Electrical Components Of Circuits
- <img src="https://files.catbox.moe/hwymit.png" width="500">
- <img src="https://files.catbox.moe/r68d9o.png" width="500">
### Mandatory Componenets
1. **Energy Source**: `Releases energy` to provide power to other componenets that are connecter
- Example Electrochemical cell, battery, electrical outlet...
2. **Load**: `Converts` electrical energy into other form of energy.
- Example: Light bulb, heater, fan, motor...
3. **Conductor**: Allows `Electricity to flow` through them easily
- Example: Copper wire, gold wire, silver wire.
### Optional Items
1. **Switch**: Turns the electric circuit ono or off **by cutting off the path**.
2. **Measuring Device**: Measures the `electrical property` of the circuit.
3. **Fuse**: `Safety device` to prevent further damage to other electrical components.
## Batteries
- `Electrochemical Cell`: A package of chemicals that converts `chemical energy into electrical energy`.
- `Battery`: More than 1 cell.
- Types of cell: `dry` (paste, like a AA battery), `wet` (liquid, like a Car battery).
### 1. Wet Cell (Voltaic Cell)
- <img src="https://files.catbox.moe/krm6sm.png" width="500">
### 2. Dry Cell
- <img src="https://files.catbox.moe/0wuuml.png" width="500">
- Rechargeable cells are called **Secondary** cells, while non-rechargeable cells are called **Primary** cells.
### 3. Specialized Cells
- **Fuel cell**
- Generates using external fuel, works like an engine without a moing part, requires continous source of fuel and oxygen.
- Generates `non-polluting` exhaust.
- **Uses**:
- Primary and backup power for commerical industrial and residential buildings.
- Power fuel-cell vehicles.
- **Solar Cell**
- Converts `light` energy into electrical energy.
- Based on semi-conductor `silicon`.
- `Very low efficiency` (the best is around 40-50% efficiency)
## Generating Electricity
- `Non-renewable energy source`: energy source that cannot be replaced as quickly as its is used.
- `Renewable energy source`: energy source that can be re-used or replaced quickly.
### Types of Energy
|Type|Example|
|:---|:------|
|Nuclear|Nuclear reaction|
|Gravitational|Ball rolling down a hill|
|Chemical|Chemical reaction|
|Kinetic|Any movement|
|Sound|Voice, music|
|Thermal|Heat from fire|
|Electricity|Lightning, electricity in your home|
|Light|Sunlight, Microwave|
### Pros and Cons
|Method|Advantage|Disadvantage|
|:-----|:--------|:-----------|
|Fossil Fuel|- very low cost to generate electricity|Create pollution during `mining` and `burning` fossil fuels.|
|Biomass|- very low cost to generate electricity <br> - `renewable` compared to fossil fuel|- create pollution during `burning` biomass <br> - can result in lower `food` production|
|Nuclear|- `low cost` to generate electricity <br> - needs very little `fuel`|- very `high cost` to construct and maintain <br>- create `radioactive` waste <br>- at risk during `natural diasters`|
|Hydroelectric|- `low cost` to generate electricity if large scale <br>- no `air` pollution|- huge `disruption` to large area of envirnoment during construction <br>- very `highcost` to construct|
|Tidal|- `low cost` to generate electricity <br>- no `air` pollution|- huge `disruption` to large area of envirnoment during construction <br> - very `highcost` to construct <br>- very `few` suitable location(s)|
|Wind|- `low cost` to generate electricity <br>- Can be built `anywhere` that has wind available|- the wind does not always blow, which means the electricity generated is `not reliable`<br>- potiential danger to `birds`|
|Solar|- Can be built `anywhere` that has sunlight available <br> - no cost on `fuel`<br> - easy to install in `remove` `areas` <br>- no `air` pollution|- Very low `efficiency`, which means a `large` are is needd to get enough sunlight <br> - generally only works during `daytime`|
|Geothermal|- `low cost` to generate electricity <br> - no `air pollution|- very `few` suitable location(s) <br>- very `high cost` to construct|
## Measurement in Electric Circuits
|Electrical Quantity|Electrical Quantity Symbol|Unit of Measurement|Unit of Measurement Symbol|Instrument Of Measurement|Symbol For Insturment|
|:------------------|:-------------------------|:------------------|:-------------------------|:------------------------|:-------------------:|
| Resistance | R | Ohms | Ω | Ohmmeter |<img src="https://www.wisc-online.com/assetrepository/getfile?id=4674&getType=view&width=0&height=0" width="200">|
| Current | I | Amperes | A | Ammeter |<img src="https://i.stack.imgur.com/sTYoJ.png" width="200">|
| Voltage | V | Volt | V | Voltmeter |<img src="https://upload.wikimedia.org/wikipedia/commons/5/59/Voltmeter_symbol.png" width="200">|
| Electric Charge | Q | Coulomb | C | ||
### 1. Electric Charge
- **Symbol** for **Electric Charge**: `Q`.
- **Unit** for **Electric Charge**: `Coulomb [C]`.
- **1C = the charge of** $`6.25 \times 10^{18}`$ **electrons (6 250 000 000 000 000 000)**.
### 2. Electric Current
- The rate (speed) of the movement of electric charge (electrons) in an electric circuit.
- **Symbol** for **Electrical Current**: `I`.
- **Unit** for **Electrical Current**: `Ampere [A]`.
- **1 A = 1 C per 1 s** = 1 coulomb of charge moved pass a point in 1 second
- In an electric circuit, there are 2 convention of how electrons flow in the circuit.
1. Conventional
- electrons flows from the `positive` terminal to `negative` terminal.
2. Electron flow
- electrons flows from the `negative` terminal to `positive` terminal.
- Correct way vuit it is not widely used.
- The electric currnet is measured by an `ammeter`.
- It is connected `in series` to the item you wnat to measure, which means you put the ammeter `infront or behind` the item you want to measure.
### 3. Potential Difference / Voltageg
- the `difference` in electrical potential `energy` when a charge moved between `2 points` in an electric circuit.
- **Symbol** for **Voltage**: `V`.
- **Unit** for **Voltage**: `Volt[V]`
- **1V = 1J of enery per 1C of charge** (each coulomb of charge have 1J have energy).
- The **voltage** is measured by a `voltmeter`.
- It is connected `in parallel` to the item you want to measure, which means you `create a new path` for the voltmeter next to the item you want to measure.
### 4. Electrical Resistance
- The `opposition` to the flow of electric current in a material. This is a property of the `material`.
- **Symbol** for **Electric Resistance**: `R`
- **Unit** for **Resistance**: `Ohms[Ω]`
- The resistance is measure by an `ohmmeter`.
- It is connected `in parallel` to the item you want to measure, which means you `create a new path` for the ohmmeter next to the item you want to measure.
- #### Reasons for resistance:
- A `load` convert `electrical energy into other energy`
- Example: light bulb convert electrical energy to light energy.
- Setup the `flow` of circuit
- Example: Resistor adjusts flow of circuit (like narrowing down a road)
- `Everything` has resistance. Conductor has low resistnace. Insulator has high resistance.
- Example: wire has an resistnace so low that it is ignored in many calculations.