2 - Electricity Flashcards
What is current
The rate of flow of charge
What does resistance do
Slows the flow of charge down
What is a ammeter for
Measures the current
What is a mains electricity supply
Alternating current (a.c)
Describe the direction of a mains electricity supply
Current is Constantly changing direction
What’s the current in cells and batteries
Direct current (d.c)
Describe the direction of cells and battery supply
Current flows in the same direction
What happens in a series circuit if one component is moved
all components stop working
What are the 3 wires in a plug
Live, neutral and earth
What happens to the resistance on a LDR if more light is shone onto it
The resistance decreases
What is a LDR
A light dependent resistor
What happens to the resistance on a thermistor when it is heated
Resistance decreases
What is a diode
A component which only allows current to pass in one direction
What happens if voltage is applied in the reverse direction
The diode has a very high resistance and prevents any current
What happens as the voltage across a component is increased
The current in the component also increases
What is the function of a fuse
cuts off the flow of electricity to an appliance if the current becomes too large
What does the earth wire do
Provides a low resistance path to the earth. (Safety)
What is the purpose of double insulation?
- Insulation around the wires themselves
- The non-metallic case acts as a second layer of insulation
What is electricity in metals caused by
A flow of electrons
Describe electricity in metal
As electrons pass through the metal they collide with ions, making them vibrate
What is an advantage of a series circuit
All of the components can be controlled by a single switch.
What are the disadvantages of series circuits
- The components cannot be controlled separately.
- If one component breaks, the others will stop working as well.
What are the advantages of parallel circuits
- The components can be individually controlled
- If one component stops working the others will continue to function.
What does the amount of current in a series circuit depend on
- The voltage of the power source.
- The number (and type) of components in the circuit
How can you test for current in a circuit ?
By using lamps and LEDs which light up when current passes through them
What is current in metal caused by
by a flow of delocalised electrons
What happens when two or more components are connected in series
- The current in each component is the same.
- The total voltage across the components is equal to the sum of individual voltages.
- The combined resistance of the components is equal to the sum of individual resistances
What is voltage
The energy transferred per unit of charge passed
High resistance =
Low current
What happens at a junction?
Current is conserved
Which wire connects to the fuse?
Live wire
