electricity Flashcards
What two factors does the current in the circuit depend on?
potential difference (V)
Resistance (R)
what is an Ohmic conductor state? The condition required?
A conductor for which current and potential difference are directly proportional
Resistance remains constant as current changes
temperature Must be constant
List four components for which resistance is not constant as current changes
lamps, diodes ,thermistor, light dependent resistors 
What happens to the resistance of a filament lamp as the temperature increases and why?
resistance increases
Irons and metal have more energy, so vibrate more, causing more collisions with electrons as they flow through the metal, creating greater resistance to current flow
what is the different about current flow through a diode
The current only flows in One Direction
resistance is very high in other direction, preventing in current flow 
State what happens to the resistance of a thermistor as temperature increases
The thermistor resistance decreases
give two examples of when a thermistor may be used
in thermostat to turn the heater on below a certain temperature
In a freezer to turn on a cooler when the temperature becomes too high
State what happens to the resistor of LDR as light intensity decreases
The LDR resistance increases
Give an application for an LDR
Street lights often use ldr
when light levels become too low, the light gains sufficient current turn on 
what are the two ways that are component can be connected in a circuit?
Series(same loop)
Parallel (adjacent loop)
how does the potential difference across two components vary when connected in series and parallel? 
series: total potential difference is shared between each component
Parallel : potential difference across each component is the same
If two resistors are connected in parallel, what can be said about their combined total resistance?
Their total resistance is less than the smallest of the two individual resistances
If two resistors are connected in series, what can be said about their total resistance?
The total combine resistance is equal to the sum of the two individual resistances
Describe the current in a series circuit
In a series circuit, the current is the same at all positions since the charge only has one path to flow through
describe the current in a parallel circuit
In a parallel circuit, the current is shared between the different branches. When the charge reaches a junction it splits.
how should you connect ammeter in circuit to measure current?
Amita should be connected in series with the component that they are measuring current through
how should you connect voltmeter in circuit to measure potential difference?
voltmetre should be connected in a parallel to the component that they are measuring the potential difference of 
Why is it advantageous to connect lamps in parallel?
if one lamp blows, the rest will be unaffected and can still receive current
Is mains electricity an AC supply or a DC supply? What did each of these stand for?
mains electricity is an AC supply
AC: alternative current
DC: Direct current
Define alternating current and direct current
alternative current: current that continuous changes direction at a specific frequency
Direct current: One Direction current flow
What is the frequency and voltage of the UK mains electricity supply?
frequency:50 Hz
Voltage: 230V
How many wires are usually in the cables connecting electrical appliances to the mains? Name these wires.
- Live wire.
- Neutral wire.
- Earth wire.
State the insulation colour used on the earth wire
Green and yellow stripes
State the insulation colour used on the live wire
Brown
