2. Electricity Flashcards
What direction do electrons flow in?
Opposite direction of the conventional current
What is charge?
The electrons that are always in a wire - whether connected to a cell or not
What is current?
The flow of electrons in a conductor - when it’s connected to a cell in a complete circuit
What is current measured in?
Amps (A)
What is voltage?
The push and pull of electrons in a wire - makes electrons flow
What is voltage measured in?
Volts
What is electrical energy?
Energy carried by current and converted to heat and light energy
Is the current the same all the way round in series?
Yes
Why do electrical charges move through metals?
They have some electrons that are free to move from their atoms
What is an electric current?
A movement of charge
What is electrolysis?
When current flows in a liquid, carried by positive and negative ions
What happens when electrical current flows through a resistor?
Electrical energy is transformed into heat energy
Another phrase for energy transferred?
Work done
What does the energy transferred depend on?
Amount of charge carried by electrons and p.d. Pushing the charge around
What is the power?
The rate at which energy is transformed
What charge do electrons have?
Negative
What direction do electrons flow in?
Opposite direction of the conventional current
What is charge?
The electrons that are always in a wire - whether connected to a cell or not
What is current?
The flow of electrons in a conductor - when it’s connected to a cell in a complete circuit
What is current measured in?
Amps (A)
What is voltage?
The push and pull of electrons in a wire - makes electrons flow
What is voltage measured in?
Volts
What is electrical energy?
Energy carried by current and converted to heat and light energy
Is the current the same all the way round in series?
Yes
Why do electrical charges move through metals?
They have some electrons that are free to move from their atoms
What is an electric current?
A movement of charge
What is electrolysis?
When current flows in a liquid, carried by positive and negative ions
What happens when electrical current flows through a resistor?
Electrical energy is transformed into heat energy
Another phrase for energy transferred?
Work done
What does the energy transferred depend on?
Amount of charge carried by electrons and p.d. Pushing the charge around
What is the power?
The rate at which energy is transformed
What charge do electrons have?
Negative
What is the unit for power?
Watt (W)
What happens to power as current increases?
Increases
What happens to a lamp when there is lower resistance?
the lamp is brighter
What do electrons have to do when passing through a wire?
Push their way through vibrating electrons
What does the resistance in a circuit do?
Limit the current
Ohms law?
The current through a resistor at a constant temperature is directly proportional to the potential difference across the resistor
What is the p.d. of cells?
The sum of the p.d. of each cell
In a series circuit…
- the same current passes through the components
- the p.d. of the voltage supply is shared between the components
- the total resistance of components is equal to the sum of the resistance of each component
In a parallel circuit…
- the total current through the whole circuit is the sum of the currents through the separate components
- the p.d. across each branch is the same
Is the voltage across each branch in parallel the same?
Yes
What happens to current as resistance of a filament lamp increases?
Increases
What does a current - p.d. graph with a straight line show?
The resistance is constant, obeying Ohm’s law.
An example of an ohmic conductor?
A wire
What does a current - p.d. graph with a curve show?
The resistance isn’t constant, it increases as the temperature increases.
What does a current - p.d. graph with a forward/reverse bias show?
The resistance is not constant, it rapidly decreased and the current increases
What component will make a forward bias?
Diode
What component will make a curve?
Filament lamp
What component will make a straight line?
A wire
What happens to resistance as light intensity increases?
It increases
What is static electricity?
When charge builds up on an object and doesn’t move e.g. rubbing a rod
What will happen when two different rods are held close to each other?
They will attract if they have different charge
What happens to materials that are oppositely charged?
They attract
What will happen when two rods of the same material are held close to each other?
They will repel as they have the same charge
What happens to materials that have the same charge?
They will repel each other
Are electrostatic forces contact or non-contact?
Non-contact forces that can act at a distance
What is an electric field?
The region where a charged object would experience a force
How is an electric field represented?
Using field lines
What does the direction of a field line show?
The direction of the force that would act on a small positive charge at that point
What does the spacing of field lines show?
The strength of the force.
The closer together the lines, the stronger the force