Unit 4 Flashcards by Aaralyn Hu

Static Electricity

Object has an imbalance in charges (friction)

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Current Electricity

Exists when charges move continuously

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Coulombs

A charge of electricity

1C = 6.25x10^18 protons or electrons

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Conductors

Materials that allow charges to move

Ex: metals, electrolytic solutions

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Insulators

Materials that prevents charges from moving

Ex: non-metals (plastic, rubber, glass, cotton)

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Charging by Rubbing

Friction
When rubbed, electrons transfer from one object to another (objects acquire different charges)

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Triboelectric series

A list that ranks materials ability to gain or lose electrons

(Easily gains electrons - negative) plastic, sulphur, gold

(Easily loses electrons - positive) glass, wool, fur, lead

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Charging by Conduction

Mouvement of negative energy from one charged object to a neutral one

Initial situation
Approach (dipole created)
Contact (charges move)
Separation (two objects of similar charges)

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Grounding

Earthing

Earth (an infinite capacity to supply or receive electrons) can make a charge object neutral when touching ground

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Charging by induction

Charging without contact, requires a third neutral object

Initial situation
Approach with charging object (dipole created in middle neutral)
Contact with third-neutral-object (to middle-neutral object - charges move)
Removal of objects (said to be charged one not touching tho suspect vice versa)

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Circuit

A network in which charges (electrons can move continuously)

Closed (moving)
Open (not moving)

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Direct vs Alternating Current

DC: Electrons moving in sole direction (symbol two lines one shorter and longer)

AC: Electrons moving in either direction (Symbol sideways backwards S)

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Power supply

Electrical function performed by any component that can generate electrical current

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Battery

Power supply (DC)
- Portable
—
- Must be replaced
- Can contaminate environment

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Electrical Outlet

Power supply AC
- Stable & long lasting
- Low GHG (if Hydro-Electric)
—
- Hydro dams flood land
- Appliance cannot be far from wall outlets
- Appliances stop working during power cut

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Photovoltaic (Solar) Cell

Power supply DC
- Can be used in isolated areas
- Power portable or mobile devices
- No GHG
- 20-30y lifespan
—
- Depends on sunny conditions
- expensive install than other power sources

Protection

Electrical function performed by a circuit component stops current flow if too high

Fuse

Protection
Conducting filament melts and breaks, preventing flow
must be replaced

Breaker

Bimetallic strip or electromagnet activates, connection broken
* switch is thrown to restore flow*

Control

Electrical function to start and stop flow

Switch

Resistance

Electrical function performed by component that decreases the current in a circuit

Symbol: squizzly lines

Energy Transformation

Electrical function performed by a component that converts electrical energy into another form of energy

(Light bulb)

Formula for Current

I = Q/t

I = Current Intensity (measures in A - amps)
Q = Charge (measures in C - Coulombs)
t = Time (measures in s - seconds)

# of electrical charges that pass a fixed point every second

Ammeter

Measures current in a circuit

Measures in series

Series: intensity stays the same

Formula for Voltage

V = E/Q V = Voltage (measures in V - volts) E = Energy (measures in J - joules) Q = Charge (measures in C - Coulombs) *Amount of energy transferred between 2 point in an electrical circuit*

Voltmeter

Measures voltage Measures in parallel

Formula for Resistance

R=V/I R = Resistance (measures in omega sign - ohms) V = Voltage (measures in V - volts) I = Current Intensity (measures in A - amps) *measure of how much a material resists the flow of electric current*

Formula for Conductance

G=I/V G = Conductance (measures in S - siemens) I = Current Intensity (measures in A - amps) V = Voltage (measures in V - volts) *Measures how much a material can allow the flow of electric current*

Graphing conductance or resistance

1. Plot out graph - y = numerator - x = denominator 2. Find line of best fit 3. Choose two point on the line (a=y2-y1/x2-x1)

Factors Affecting Conductance (vice versa for Resistance)

- Thickness: Thick (diameter)✅ - Length: Short (distance)✅ - Temperature: Cooler ✅ - Material

Formula for Power

P=VxI P= Power (measures in W - watts) V = Voltage (measures in V - volts) I = Current Intensity (measures in A - amps) *Electrical energy converted into work (heat, light, etc) every second*

Formula for Energy

E (energy) =P (power) x t (time) J (joules) = W (watt) x s (second) W-h (Watt-hours) = W (watt) x h (hour) kW-h (kilowatt-hours) = kW (kilowatt) x h (hour)

Series circuit

There’s only one path for current flow *If one component breaks, the circuit stops working since flow of electricity is interrupted*

Parallel Circuit

There are multiple paths for current flow *If one component breaks, the circuit continues to work since flow of electricity is not interrupted*

Conventional Current

Movement of positive charges (from longer line + to shorter line -)