6. Safety devices are important in household circuits 1. discuss the dangers of an electric shock from both a 240 volt AC mains supply and various DC voltages, from appliances, on the muscles of the body When muscles of the body are exposed to electric shock, the muscles contract the heart muscle goes into fibrillation (this is when the heart beats irregularly) electric shock can result in death AC is much more dangerous than DC. 2. describe the functions of circuit breakers, fuses, earthing, double insulation and other safety devices in the home Circuit breakers work by shutting off electricity when the current exceeds a safe level. Fuses do the same thing but work by allowing the fuse wire to melt when the current is too high. Circuit breakers are much more common in houses than fuses, as circuit breakers only need to be reset, whereas fuses need to be replaced. Earthing refers to allowing excess current to go to the ground instead of building up and causing potential problems. In a standard power point the bottom pin is used for earthing. Double insulation in coating the wire twice (with non-conductors), this means that if one fails the other coating will protect you.
6. Safety devices are important in household circuits 1. discuss the dangers of an electric shock from both a 240 volt AC mains supply and various DC voltages, from appliances, on the muscles of the body When muscles of the body are exposed to electric shock, the muscles contract the heart muscle goes into fibrillation (this is when the heart beats irregularly) electric shock can result in death AC is much more dangerous than DC. 2. describe the functions of circuit breakers, fuses, earthing, double insulation and other safety devices in the home Circuit breakers work by shutting off electricity when the current exceeds a safe level. Fuses do the same thing but work by allowing the fuse wire to melt when the current is too high. Circuit breakers are much more common in houses than fuses, as circuit breakers only need to be reset, whereas fuses need to be replaced. Earthing refers to allowing excess current to go to the ground instead of building up and causing potential problems. In a standard power point the bottom pin is used for earthing. Double insulation in coating the wire twice (with non-conductors), this means that if one fails the other coating will protect you.
Prelim_Phys_Notes.docx