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## PowerPoint Slideshow about ' Electricity' - belle

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### Electricity

The flow of charges

Atoms

- Made up of:
- Nucleus: Protons and neutrons
- Electrons: negative charge orbit nucleus

Current

- Flow of electrons
- Measured in Amperes (Amps)
- Electrons passing per second

- Measured in Amperes (Amps)

Circuit

- Must have complete, unbroken path for current to flow
- 3 Parts:
- Load: device run by electricity
- Wires: path for electron flow
- Source: moves the electrons through the wire
- Battery, generator, wall socket (power plant)

- 3 Parts:

Conductors

- Materials allowing electrons to flow
- Examples:
- metals: electrons loosely held, move easily
- Copper is one of the best

- metals: electrons loosely held, move easily

- Examples:

Insulators

- Do not allow electricity to flow
- Examples: rubber, plastic
- Electrons held tightly, will not move easily

- Examples: rubber, plastic

Voltage

- Measures the force “pushing” electrons
- Volt (v) as unit
- Higher voltage is higher potential to push electrons through circuit

- Volt (v) as unit

Resistance

- Force working against (“resisting”) the flow of electrons
- Measured in Ohms (Ω)
- All parts of circuit “slows the flow”

Practice Ohm’s Law

- A 9 volt battery is used to light 3 bulbs with a resistance of 0.5 Ω each. Wires and a switch add another 3 ohms of resistance. How much current (amps) is flowing through the circuit?
- Plan
- What information is given?
- 9 volts, 3 bulbs x 0.5 ohms = 1.5 ohms plus 3 ohms for total of 4.5 ohms.

- What formula do I use?
- I = v / r
- I = 9 v / 4.5 Ω

- Solve
- I = 2 amps

- Check:Does it make sense?
- The current is less than the voltage because the resistance is reducing the flow

- Plan

Series Circuit

- Only one path for electricity to flow
- What happens if one bulb goes out?
- Will the bulbs be dimmer or brighter than a parallel?

Load (bulb)

Switch

Parallel circuit

- More than one path for electricity to flow
- Each load on separate circuit
- What happens if one bulb goes out?

- Compare series/parallel to water supply

Direct CurrentDC

- Charges always flow in same direction, from negative terminal to positive terminal
- Battery (cells)

plastic seal

plastic sleeve

anode

steel jacket

Case sleeve

Cell straps

cathode

Negative terminal

cathode collector

electrolyte

Positive terminal

Cells and Batteries9 Volt Battery

- Convert chemical energy to electrical energy
- Potato clock

Electron acceptor

Electron donor

Other sources of DC

- Thermocouple: convert heat to electricity
- Solar cells: convert solar energy to electricity

Alternating CurrentAC

- Charges flow from negative to positive but switch directions back and forth (alternate)
- House current

Producing AC current

- Induction: Coil of wire and magnet produce electricity
- It’s electro-magnetism!
- Generator: converts mechanical energy to electrical energy
- Motor: converts electrical energy to mechanical energy

Electromagnetism

- Magnetism and Electricity are closely related
- Electric current causes magnetic fields
- Cell phones, television, light

- Magnets can cause an electric current to flow
- Generators

Power

- Measures how fast energy is transferred from one form to another
- Measured in Watts
- Power = voltage x current
- P= V I
- A 100 watt light bulb changes or uses electrical energy to light energy twice as fast as a 50 watt bulb

- Power = voltage x current
- Brainpop on current

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