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electrical by Mind Map: electrical

1. 13.3

1.1. Electric current effects:

1.1.1. Chemical effects Coating medical instruments: Electroplating the instruments with a protective layer can minimise damage and lengthen their lifespan. Metals like gold, silver and copper are often used as they have antibacterial properties → can destroy harmful microorganisms Minimises infections and ensure they are clean and safe to use Coating for implants Implants are often electroplated because it makes it stronger and durable However, some metals can cause allergic reactions and are more likely to be rejected by the body after surgery Coating the implants with living tissue (e.g. a biocompatible material) would reduce the risk of infection and rejection by the body Heating effects When an electric current passes through a heating element, some electrical energy may be converted to heat energy. (Heating element usually made of high resistance materials like nichrome) Medical devices also use the heating effect Magnetic effect When an electric current flows through a wire placed near a compass, the needle in the compass is deflected Electromagnets are also created using this effect Other examples of this effect are: robot systems designed to assist surgeons, MRI machines (which creates detailed images of the organs and tissues in the body), etc.

1.1.2. Harmful effects Electrical fire When the circuit is damaged or multiple plugs are inserted in the same circuit (overloading), a very large amount of current may be drawn from the power supply, which may cause the wires to melt and cause an electric fire. Electric Shock Water is an electrical conductor which allows current to flow so we should avoid putting electrical appliances such as hair dryers near them and instead in dry places and handled with dry hands It may also occur when we insert our fingers into sockets. We should use a two-pin plug adaptor instead of inserting a random object in and we should also switch off the power supply before removing the plugs or washing an electrical appliance.

1.1.3. Safety devices in our household Fuse When there is an abnormally large current flowing through the appliance, the wire in the fuse would melt causing the circuit to open which means that no current would be able to flow through the appliance. After the fault in the appliance is corrected, one must replace the fuse in the appliance before using the appliance again. Circuit breakers Found in our homes: Residual Current Circuit Breaker (RCCB) The RCCB has many individual lever-like switches and the switches are linked to different appliances in the household. When the current flow is too large, the appliance trips and cuts off the current

2. 13.4

2.1. Consumption of electrical energy

2.1.1. Annual energy consumption It depends on the rate of electricity consumption by the appliance. Amount of electrical energy used for the conversion into other forms of energy per unit time is referred to as the power of the electrical appliance. SI unit of power is watt (W) 1 kW = 1000W

2.1.2. Cost of electrical energy consumption Unit is kWh (kilowatt hours) Formula: electrical energy (kWh) = power (kW) x time (h) To find the cost of the electrical energy consumption we use the kWh amount x the electric tariff (currently 30.17 cents in sg)

2.1.3. Ways to conserve energy Buy appliances with energy labels with three or more ticks Switch off the air conditioner after a short while and turn off the fan Switch off the water heater after use Use a vacuum flask instead of an electric hot water dispenser Switch off the power socket to reduce standby power.

3. 13.2

3.1. Rate of electrical charge flows = electric current

3.2. Measurement of electric current = how much electric charge flowing past a particular point in an electric circuit per unit time

3.2.1. an ammeter is used to measure this SI unit for current is ampere (A) Ammeter must be connected in series to the circuit to get the full current flowing through a branch and must have a small resistance to limit its effect on the circuit.

3.3. Amount of energy needed to move an unit charge from one point to another in the electrical circuit is the potential difference/voltage (V)

3.3.1. Voltmeter is used to measure voltage SI unit is volt (V) Voltmeter has to be connected in parallel to the circuit

3.4. Electrical resistance (R) is how much the component opposes the flow of electric current

3.4.1. Insulators = high resistance

3.4.2. Resistor SI unit is ohm

3.5. Electric conductors

3.5.1. High resistance which allows it to convert the electrical energy into other forms of energy (e.g. tungsten, nichrome)

3.5.2. Low resistance (e.g. copper, silver) = good conductors of electricity

3.6. Electrical insulators

3.6.1. High resistance → does not allow current to flow (e.g. plastic, glass) Resistor = harder for electric charge to flow → current flowing through bulb decreases → bulb becomes less bright Two types of resistors: fixed resistors and variable resistors

4. 13.1

4.1. remember the electrical component and its corresponding symbols

4.2. rmb to watch out for the direction of the battery

4.2.1. shorter end is negative, longer end is positive