SP10 Flashcards
(32 cards)
What is voltage?
It is a measure of the difference in electrical energy between two parts of a circuit (potential difference). The bigger the difference in energy, the bigger the voltage. it ‘pushes’ the current around and is measured in volts (V).
What is current?
The flow of electric charge. measured in amps (A)
What is the conventional current direction?
from the positive terminal to the negative terminal of the battery
What is resistance?
The force that opposes or resists the flow of electrons in a circuit
Why does temperature affect resistance?
When temperature is increased, this causes the ions to vibrate more vigorously, causing more collisions
Why do graphs for diodes only show a current when the PD is positive?
They have a really high resistance in the opposite direction so no current can flow in that direction
What is charge?
A measure of the total current flowed within a certain period of time
What does Ohms Law state?
V=IR
What is the same everywhere for series circuits?
Current
What is shared in series circuits?
Voltage
In a parallel circuit, Vtotal=
V1=V2=V3=V4 and so on
In a parallel circuit, I total=
I1+I2+I3.. and so on
What happens when you increase the amount of components in a parallel circuit?
The total resistance lowers
What is the formula for charge?
Current x time (seconds)
What is the formula for energy transferred?
Energy transferred = Potential difference x Charge
How is energy transferred through a circuit?
A cell (or battery) containing energy transfers this to the charge The charge transfers the energy to the components The components (eg lamp) transfer the energy to the surroundings by heating and light
Why do resistors get hotter when current flows through it?
As current flows through, ions in the resistor collide with the electrons. This converts kinetic energy into thermal energy, increasing the resistor’s temperature
What is the formula for power? (use energy transferred)
Energy transferred/time= power
Give the two formulae for working out power (using current)
Current x potential difference
and
Current² x resistance
What is the national grid?
A network of wires and cables that transfer electricity to our homes
What is AC?
Alternating current, current that constantly changes direction
What is DC?
Direct current, current that travels in one direction
What is the frequency and voltage of mains electricity?
230V and 50Hz
What does the live wire do?
Provides the voltage for the circuit
