Flashcards in Physics 6 Deck (85)
What is static electricity ?
Electricity that is not free to move
What happens when two insulating materials are rubbed together ?
Electrons will be rubbed off one, on to the other
True or False - only electrons move
True - negative charges are formed when electrons move to the material. Positive charges are caused by electrons moving elsewhere
What is current ?
The flow of electric charge round a circuit
What is potential difference ?
The 'driving force' that pushes current round
What is resistance ?
Anything which slows the flow down in the circuit
The greater the resistance over a component, the .....
Smaller the current that will flow
What is current measured in ?
How do you work out the current in a circuit ?
Charge divided by time
What is potential difference measured in and how do you find it ?
Volts, it is the amount of energy transferred (work done) per unit of charge. So...
Work done divided by charge
How do you measure the current flowing through the component ?
Using an ammeter. It can be placed anywhere in series
How do you measure the potential difference across a component ?
Using a voltmeter. It must be placed in parallel around a component
What is a standard test circuit ?
One of the simplest circuits you can make. It is use to test components and find V-I graphs
What does a variable resistor do ?
Alters the current flowing through a circuit
Why does a V-I graph of a filament bulb curve ?
As the temperature of the filament increases the resistance increases
Why does resistance increase with temperature ?
When an electrical charge flows through a resistor some of it is converted into heat energy. The ions vibrate more because they are heated, making it harder for charge- carrying electrons to get through
What does Current x Resistance =
What does a diode do ? How does it do this ?
It regulates potential difference in a circuit by only letting current through in one direction
What does a light emitting diode do ?
Emits light when a current flows through in a certain direction
What does an LDR do ?
It changes it's resistance depending on the intensity of light. In bright light the resistance falls and in darkness the resistance is high
What does a thermistor do ?
It's resistance depends on the temperature. In hot condition the resistance is low and vice versa
What is a series circuit ?
When all the components are connected in a line. If one component is disconnected the circuit breaks.
What is shared an what is the same in a series circuit ?
Potential difference is shared and current is the same
How is potential difference shared ?
If a component has more resistance it has a bigger share I the potential difference
What is a parallel circuit ?
When each component is separate. If one component is disconnected it will continue to work.
In a parallel circuit what is shared and what is the same ?
Potential difference is the same and current is shared
What is the UK mains supply ?
What I the frequency of the AC mains supply ?
What is the difference between mains supply (AC) and battery supply (DC) ?
Alternating current goes back and forward but direct current travels in the same direction