Electricty In The Home Flashcards
What are the 2 types of current
Alternating current
Direct current
What is the brown wire in the plug
LIVE WIRE- provides the alternating potential difference at about 230v
What is the blue wire in a plug ?
NEUTRAL WIRE- completes the circuit and carries away the current . Current flows in the live wire and out through the neutral wire
What is the brown and yellow wire in the plug?
EARTH WIRE- used to protect the wiring and for safety , it prevents the case from becoming live if a fault is detected
Energy transferred equation
Power x time
What is the equation that links energy transferred and charge flow
Energy transferred = charge flow x potential difference
What is the equation that links power and current
Power = current x potential difference
What is the national grid
A giant system of cables and transformers that covers the UK and connects power stations to consumers
Why does the national grid use a High PD and a low current
To transmit lots of power on of these values must be high however if the current gets to big then wires will heat up and energy will be transferred to thermal energy whereas using a high PD is easier . This means no energy is transferred to a thermal energy store.
Why are transformers used
The transformers must step the PD up at one end to allow an efficient transmission but then step it down so it is at a safe and usable level
How can electrons be transmitted from one material to another
When certain insulating materials are rubbed together negatively charged electrons will be scarped off one and dumped on the other .
Positive charges do not move as they are in the nucleus
How do sparks appear
If the Potential difference is high enough a strong electric field is created . This ionises the air molecules allowing a current to pass through them
How does resistance change with an LDR
Changes with light intensity
When light intensity increases LDR decreases
How does resistance effect potential difference on a component
If resistance decreases so does the potential difference of the component
