Electricity Flashcards
1
Q
Household electricity
- direct current (examples)?
- alternating current?
- mains supply = a.c/d.c? = frequency? + voltage?
- how can u rectify a.c?
- PLUGS!!
- if electrical fault means too great a current flows then…..?
- what happens when current exceeds fuse rating?
- what are rccbs?
- appliances with metal cases are usually…..?
- which items together protect the wiring of the circuit?
A
- dc= current in same direction (cells and batteries)
- ac= in two directions (constantly changing)
- mains= ac = 50cycles per second = 230V
- using a diode
- circuit is disconnected by a fuse or circuit breaker in the live wire
- fuse melts
- = detect difference in current between Live and neutral wires
- earthed (some are double insulated)
- earth wire and fuse
2
Q
Electrical circuits
- what is electric current?
- materials that charges can move easily through?
- equation for current?
- equation for potential difference?
- SYMBOLS!!
- resistance can be found by….?
- greater resistance the …… the current for a given voltage across the component?
- resistance equation?
A
- current = flow of electric charge
- easily through conductors of electricity- eg metals
- current= charge/ time
- potential difference= energy/ charge
- by measuring the current through and potential difference across the component
- the smaller the current
- voltage= current x resistance
3
Q
Transferring electrical energy
- power=?
- equation for power?
- equation for power and voltage?
- energy transferred equation?
- electrical appliances are designed to…?
- amount of energy an appliance transfers depends on…? (2 things)
A
- power= energy/time
- power= current x voltage
- energy= voltage x charge
- designed to bring about energy transfers
- = how long it’s switched on for + its power
4
Q
National grid
- electricity along national grid from….?
- for a given power, increasing voltage =? (For current required and energy losses)
- what are used to change voltages in the national grid?
A
- power stations
- reduces current required + reduces energy losses
- step up and step down transformers