Electric Cells Overview

Elektriese Selle

• Definisie: Elektriese selle, of battery cells, is devices that convert chemical energy into electrical energy through electrochemical reactions.

• Basiese Komponente:

  • Anode: Negatief gekonterde elektrode waar oksidasie plaasvind.
  • Katode: Positief gekonterde elektrode waar reduksie plaasvind.
  • Elektroliet: Geleier van ioniese bewegings wat die anode en katode skei.

• Werkingsbeginsel:

  • Chemiese reaksies tussen die anode, katode en elektroliet genereer elektrone.
  • Elektrone vloei van die anode na die katode deur 'n externe stroombaan, wat 'n elektrisiteitsstroom veroorsaak.

• Tipes Elektriese Selle:

  • Primêre Selle: Eenmalig gebruik, nie herlaaibaar (bv. Alkaliese batterye).
  • Sekondêre Selle: Herlaaibaar (bv. Li-ion, loodzuur batterye).

• Toepassings:

  • Voeding van elektroniese toestelle (bv. afstandbeheer, mobiltelefone).
  • Aangedrewe voertuie (bv. elektriese motors).
  • Energiebergingsoplossings (bv. sonkragstelsels).

• Belangrike Kenmerke:

  • Spanning (Volt): Energiemaat van die sel.
  • Kapaciteit (Ah): Hoeveelheid energie wat 'n sel kan stoor en lewer.
  • Levensiklus: Aantal herlaai / ontladings voordat die sel sy doeltreffendheid verloor.

• Gevolge van ou batterye:

  • Moet korrek weggegooi word om omgewingsbesoedeling te voorkom.
  • Herwinning van materiale soos lood, nikkel, en lithium is belangrik.

• Navorsing en Ontwikkeling:

  • Verbetering in batterye se energiedigtheid en laaityd.
  • Ontwikkeling van volhoubare en hernubare energiebronne saam met elektriese selle.

Electric Cells

• Definition: Electric cells, or battery cells, convert chemical energy into electrical energy via electrochemical reactions.
• Components:
  • Anode: Negatively charged electrode where oxidation occurs.
  • Cathode: Positively charged electrode where reduction occurs.
  • Electrolyte: Conducts ionic movement, separating anode and cathode.
• Working principle:
  • Chemical reactions between anode, cathode, and electrolyte generate electrons.
  • Electrons travel from anode to cathode through an external circuit, creating an electric current.
• Types of Cells:
  • Primary Cells: Single use, non-rechargeable (e.g. alkaline batteries).
  • Secondary Cells: Rechargeable (e.g. lithium-ion, lead-acid batteries).
• Applications:
  • Powering electronics (e.g. remote controls, mobile phones).
  • Electric vehicles (e.g. electric motors).
  • Energy storage solutions (e.g. solar power systems).
• Key Features:
  • Voltage (Volt): Measures the cell's energy output.
  • Capacity (Ah): Amount of energy a cell can store and deliver.
  • Cycle Life: Number of charge/discharge cycles before the cell loses efficiency.
• Consequences of Old Batteries:
  • Dispose correctly to prevent environmental pollution.
  • Recycling materials like lead, nickel, and lithium is crucial.
• Research and Development:
  • Improving battery energy density and charging time.
  • Developing sustainable and renewable energy sources alongside electric cells.

Electrical Cells and Circuits

• An electrical cell is a system where chemical reactions cause the flow of electricity through an external circuit.
• Cells are sources of electricity.
• A battery is a collection of cells connected together.

Resistance

• Conductors heat up when electrical current flows through them, some energy is lost as heat.
• All conductors have resistance.
• A resistor is a conductive material used to control the flow of electricity or provide useful energy transfer, examples include light bulbs, rheostats, motors, and light-emitting diodes.

Factors Affecting Resistance

• Type of material: different conductive materials have different resistance to electrical current
• Thickness of the conductor: thinner wires have more resistance than thicker wires
• Length of the conductor: longer wires have more resistance than shorter wires
• Temperature of the conductor: warmer conductors (metals) have higher resistance than colder conductors.

Series Circuits

• When cells are connected in series, the total voltage is the sum of the voltages of individual cells.
• Resistors can be connected in series in a circuit.
• The total voltage across the battery is the same as the sum of the voltages across each resistor.
  • A resistor with higher resistance will have a higher voltage across it.
  • A resistor with lower resistance will have a lower voltage across it.
• Current is the same when measured at any point in a given series circuit.
• The total current in the circuit decreases with the addition of each resistor in series.

Parallel Circuits

• When cells (with the same voltage) are connected in parallel, the voltage across them all is the same as for one cell.
• Resistors can be connected in parallel in a circuit.
• The voltage across each resistor connected in parallel is the same.
• The total current through the battery is the same as the sum of the currents through the resistors.
• The total current in the circuit increases with each resistor added in parallel.
• The lighting system in our homes is usually connected in parallel.
• Illegal connections to the Eskom network supply can be dangerous and are considered energy theft.

Energy and the National Electricity Network

• Electricity generation:
  • Non-renewable electricity generation methods: use fossil fuels like coal, natural gas, oil, and nuclear power
    • Fossil fuels are formed from plants and animals buried deep underground millions of years ago.
  • Renewable electricity generation methods: use renewable sources such as solar energy, wind energy, hydropower, geothermal energy, and biomass to generate electricity.

How Coal Power Stations Work

• Electricity is the flow of electrons.
• Most power plants heat water to form steam which turns turbines, which in turn rotate a generator.
• A generator is a machine that produces an electric current by rotating a coil of wire within a magnetic field.
• The electricity is then channeled to the national electricity network.
• Disadvantages of coal power stations include the formation of acid rain and contributing to global warming.

Nuclear Power in South Africa

• Uses nuclear reactions (nuclear fission and nuclear fusion) to generate usable heat and electricity.
• Serves as an alternative energy source and provides 5% of South Africa's energy needs.
• The element Uranium is used as fuel and is mined from rock minerals.
• Koeberg Nuclear Power Station (Cape Town) is the only commercial nuclear power station in South Africa.
• Advantages: Uses a sustainable energy source.
• Disadvantages: Produces radioactive waste.

Coal vs Nuclear Power Stations

• The same process is followed, only the fuel source differs.

National Electricity Network

• A network of cables, masts (pylons), and transformers to distribute electricity across the country.
• Steps to provide electricity to consumers:
  • Generation: using an energy source to generate electricity.
  • Transmission: using high-voltage lines to distribute electricity from power plants to remote areas.
  • Distribution: using low-voltage lines, substations, and transformers to supply electricity to local consumers.

Cost of Electrical Power

• Electrical power is the rate of electrical energy supply, measured in watts (W) or kilowatts (kW), e.g., 800 W or 2000 W.
• Our energy consumption is calculated in kilowatt-hours (kWh).
• Formulas:
  • kWh = power of the device (kW) x number of hours used (h).
  • Cost = kWh x unit price of electricity
    • e.g., Cost = 2 kW x 150 hours x 79.5 c = 23 850 c or R238.50