P2.4 Main electricity and power Flashcards
What do electrical appliances do to energy?
They transfer energy
The power of an electrical appliance is…
…the rate at which it transforms energy
Why do appliances have their power and the potential difference of the supply they need printed on them?
So that we can CALCULATE their CURRENTand the FUSE they need
What is the frequency and the period on an oscilloscope?
Frequency= number of oscillations per second Period= time taken for one complete oscillation
What is the equation for the frequency and period?
Frequency=1/period
What is the frequency for the a.c. supply in the UK?
50Hz
Describe the structure of electrical cable
3 wires,
Copper core (conductor)
Flexible plastic covering (insulator)
What are the three colours and names of the wires, and which directions do they go?
Blue, neutral, goes to the left
Green and yellow stripe, earth, upwards
Brown, live, right
What are the four features (and materials) in a three-pin plug
- Tough, insulating CASE
- 3 brass PINS (conductors)
- FUSE between live terminal and live pin
- Cable GRIP to grip cable itself, not the wires
If an electrical fault causes too great a current, how is the circuit is disconnected?
- Circuit breaker
- RCCB
Compare the action of an RCCB to that of a fuse (2 marks)
-RCCB Detects a difference in the current
between live and neutral
-Fuse overheats and melts
What are the advantages of an RCCB?
RCCB- Faster, more sensitive, can be reset
What are the disadvantages of a fuse
- Fuse is slower
- Fuse must be replaced
What do the earth wire and fuse do together?
They protect the wiring of the circuit
What is the link between cable thickness and fuse value?
The thicker the cable, the higher the fuse value
