Electricity (Test #2)

• Particles that make up an atom: proton(positive charge, located in nucleus), electron(negative charge, surrounding nucleus), neutron(neutral/no charge, located in nucleus)
• Static electricity is the build up of electric charge (negative and negative repel). It is produced when two materials are rubbed together. Negative electrons go from one material into the other. The material the electrons leave is positively charged and the material the electrons go to is negatively charged.
• Electricity is built up and jumps over to the negatively charged object which creates a spark.
• Examples of static electricity: rub balloon against hair, walking across carpet and touching a doorknob
• Lightning is the result of static electricity discharge
• An electrical current is the path down which charge flows (electrons moving down a wire)
• For an electrical circuit to happen you need an energy source(supplies electrons with the energy they need, a battery, PowerPoint, or generator), an energy user(converts the energy the electrons deliver to them, light globe, heating element, fan), and wires, to connect everything and make the circuit complete.
• Current is measured in amps (A) using an ammeter
• Voltage is a measure of the amount of energy supplied by the power source and used by the energy user. Voltage is measured in volts (V) using a voltmeter
• AC- alternating currents, electrons move back and forth along the wire, get power from powerpoint's.
• DC- direct current, electrons move in the same direction, get power from batteries
• A battery is a source of portable electrical energy made of small cells. A cell is a single device that converts chemical energy into electrical energy, a battery is a collection's of cells.
• Wet cells- contain sulphuric acid, provide larger voltages, last a long time, easily recharged, heavy, and can leaka(car battery)
• Dry cells- contain no liquid, are compact and can't leak
• Photovoltaic/solar cells- use solar energy to create electricity (solar panels)
• Series circuit- all components connected in a single loop with one pathway for electricity to flow through
• Voltage is measured before and after current components because a voltmeter compares the energy of electrons before and after they pass through a component (for example, a light globe)
• Voltage drops occur when electrons loose energy as they pass though a component
• Resistance is a measure of how difficult it is for electrons to pass through a material. Measured in ohms (omega) with an ommeter/multimeter
• Variable resistors let you change their resistance so they can be used to control the voltage and current flowing through components in a circuit
• Some materials will conduct electricity better than others because because they have a lower resistance
• The resistance of a wire depends on: the type of material the wire is made from, the length of the wire (longer=more resistance), and the thickness of the wire (thinner=more resistance)
• Some materials are chosen for specific purposes in electrical devices because the properties of specific metals make them more suitable for some purposes than others. For example, copper is cheap so it is used a lot, and aluminium is light so it is used to make transmission lines.
• Components in a series circuit have the same current through them but split the voltage between them.
• Components in a parallel circuit have the same voltage across them but split the current between them.
• Series circuits aren't very practical because the components can't be controlled individually, the current stops flowing if one of the components breaks and the whole circuit stops working, and the more components that are added, the less voltage each one recieves
• Powerpoints and plugs have three wires, the active wire( brown), the neutral wire(blue) , and the earth wire (green and yellow)
• The active wire- carries the current to the powerpoint. The neutral wire- carries the current away from the powerpoint. The earth wire- connects the powerpoint to the earth beneath to avoid electrocution
• Fuse wires- have high resistance and a low melting point. They will Melt and break the circuit of too much current flows through it
• Circuit breakers- a switch activated by higher than normal currents (short circuits). When this happens, the circuit breaker turns off and breaks the circuit.