Unit 11: Electricity and Lighting Flashcards
semi conductors
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor and an insulator
good conductors
Good conductors are substances which allow electricity to pass through them easily.
bad conductors
Bad conductors are substances which do not allow electricity to pass through them easily.
Use of rubber and plastics in covering electrical wires and
connections.
to prevent shocks when we touch them. our body can conduct electricity, so when we hold the current-carrying wire without any covering, the current flows through our body which gives us a shock.
Energy consumption
power x time
explain the relationship between voltage, current and resistance in circuits
The relationship between current, voltage and resistance is expressed by Ohm’s Law. This states that the current flowing in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit, provided the temperature remains constant.
explain how a fuse works as a safety device;
The fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.
Colour code in wiring plug
(L) = Live = Brown. (N) = Neutral = Blue. (E) = Earth = Yellow & Green
when are flex cables used
Flexible cables are generally used in applications that require constant bending. The main advantage of a flex cable is its ability to withstand the stress associated with constant flexing motions.
dangers of overloading circuit
(overheating of wire that may cause insulation to burn).
An overloaded circuit is a significant source of potential house fires. Overloading a circuit causes an increase in temperature because of the increased electrical resistance. The wires can overheat from this overexposure over time, starting a deadly fire in the surrounding area.
discuss first aid methods for treating electrical accidents;
(i) electrical shock; and,
(ii) burns.
(i) electrical shock;
electrical shocks can cause burns, unconsciousness and even death. do not touch a victim of an electrical shock until you are sure that he is not still touching the sources of the electricity. turn the source of electricity off or use an insulating material, such as a broom handle to push the victim away from it. if the victim has stopped breathing, you must give them mouth to mouth resuscitation. keep the victim warm by placing a blanket over them and give them a hot drink such as chocolate milk, to help them get over the shock.
(ii) burns.
first degree burns makes the skin turn red and are painful but cause no lasting damage. no treatment is necessary, however, creams and sprays can be used to reduce the soreness.
Second degree burns are deeper and result in blistering. these should be treated by a nurse or a doctor. the burn area will heal over time.
third degree burns destroy the skin tissue so that it will not grow back. this is the severest form of burning and must be dealt with in a hospital. it can only be repaired by grafting skin from other parts of the body onto the damaged area.
Description of methods to include principles of CPR.
discuss the hazards associated with electricity;
Hazards associated with powerlines to include:
(i) Illegal connections;
(ii) kite flying; and,
(iii) picking of fruits.
what are the elements required for fires
(heat, fuel, oxygen).
Types of fires:
Types of fires:
(i) Electrical; are fires that result from electrical equipment malfunctioning or overheating. the fire can be tackled by covering the device in a towel or blanket, to prevent oxygen reaching the fire, or by using carbon dioxide or dry powder extinguisher. water extinguisher should never be used on electrical fires
(ii) Chemical; produce poison gases. when tackling this fire, fire fighters must wear a breathing apparatus to breathe clean air from the tanks.
(iii) Bush fires; to limit a fire to a small area is by cutting firebreaks in the direction that the fire is heading. if fire is threating peoples homes large amount of water can be dropped in it by aircraft
