- If damaged -----> live parts could be exposed and you could get a shock
- Frayed -----> live parts may not be covered
- Too long -----> trip hazard
- No water near electrical objects -----> very good conductors
- Metal conducts electricity -----> shock
Earthing and fuses:
- If a fault develops -----> case is earthed down to earth wire
- Surge in current -----> blows (melts) the fuse which cuts of live supply
- Isolates the whole appliance -----> impossible to get an electric shock -----> prevents fires
Resistors:
- electric current -----> energy transfer
- heating effect -----> increases resistance
- can cause components to melt -----> circuits stop melting
- Fuses use the effect to protect circuits
- Advantages: good for toasters and old style light bulbs -----> due to heat
Electrical Power -----> rate at which an appliance transfer energy
- high power rated appliances transfer a lot of energy in a short time; energy comes from current
- fuses are rated
- Power is measured in watts
Electrical Power = Current x Voltage
P = I x V
Circuit breakers > Fuses:
- electrical safety devices -----> (like fuse) protect circuit from damage
- detect a surge and break the circuit opening a switch
- can be easily reset -----> more convenient than fuses (they melt and have to be replaced)
When a current flows through a component, energy is transferred
Energy Transferred = Current x Voltage x Time
E = I x V x T
Alternating Current:
Direct Current:
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