Electricity

• The simplest electric circuit consists of a battery, wires, switch and a device (like a light bulb)
• How electricity works: a current of electrons is passed through a wire, from the negative terminal to positive terminal. A circuit must be complete
• Current: the movement of electrons through a circuit
• Current is measured with ammeter, symboled as I, and units are amps (a)
• Voltage: the energy to push electrons through a circuit
• Voltage is also called potential difference
• Instrument for voltage is voltmeter, symbol is V, and unit is volt (v)
• Resistance: the slowing down of electrons
• Instrument for resistance is ohmmeter, symbol is R, unit is ohm
• Bulbs in series: the current is the same in each light bulb. The problem is that if one breaks, the others won’t work
• Bulbs in parallel: some current passes through each one, and they’re parallel to one another
• Fixed resistors have one value for resistance
• Variable resistors have a range of values for resistance
• Current is directly proportional to voltage
• To keep temperature constant, a resistor like coil is usually kept in water or glycerol
• Electrical circuit: changes electrical energy into forms of energy
• Electronic circuit: processes information and makes a decision
• Buzzer: a device that converts electrical energy into sound energy

  
• Diode: a device that allows an electric current to flow in one direction only

  
• Diode allows current to flow if the P terminal is connected to the positive of the battery and the N terminal is connected to the negative of the battery
• Light emitting diode: diodes that emit light when current flows through them

  
• An LED used only a very small current when emitting light, and they’re cheaper than batteries
• Light Dependent resistor: a resistor whose value of resistance can change, it will change as the intensity/brightness of the light falling on it changes

  
• Electricity is generated from fossil fuels (coal, oil, natural gas)
• 1. fossil fuels store chemical energy, when burned they release heat energy 2) the heat energy boils water to make steam 3) the moving steam has kinetic energy, which turns blades of turbine 4) turbine spins the magnet near the coil of wire in the generator which makes the electrical energy