elec equations Flashcards
What is current?
measure of flow of electrons around the circuit
Rate of flow of charge
What is potential difference?
force driving the electrons around the circuit
What is resistance?
Everything that resists or opposes the flow of electrons
How do electrons move throughout a circuit?
positive to negative
bigger to smaller line
relationship between voltage and current
V = IR
- Directly proportional, linear through 0 with an IV graph
Describe the filament lamp IV graph and explain it
- Starts going straight up, but then plateaus
- This is because the filament becomes hot enough to produce light
- High temperature means high resistance which means higher voltage is required to push the current
How do diodes work and what do their IV graphs look like
- Prevent flow of current in one direction by having a really high resistance in that direction
- This causes there to only be a current in one direction on the IV graph
How does an LDR work?
- Higher light intensity, lower resistance
How does a thermistor work?
- Higher temp, lower resistance
What is charge?
- measure of total current that flowed within a certain time
What is the equation for charge?
Q = I x t
How is voltage measured in series?
- Potential difference of battery is the total of potential difference around each component
How is current measured in a series circuit?
- Current is same within part of each circuit
How is resistance measured in series?
- Total resistance is sum of resistance around each component
How is voltage measured in parallel?
- Parallel circuits have the same voltage in each loop
How is current measured in parallel?
- Total of each loop’s current is the total current
How does resistance work in parallel?
- Resistance reduces the more components there are
- This is because there are more paths for charge to flow, reducing overall resistance
How does a resistor work when current passes through it?
There is an energy transfer which heats the resistor due to collisions between the electrons and the ions in the lattice
- heat is dissipated to the surroundings when electric current does work against electric resistance
How do low resistance wires help with energy loss?
- Low resistance means that the current has to do less work against resistance, which therefore means less heat being dissipated to the surroundings
Advantages and disadvantages of heating affect in a current
Disadvantages:
- Reduces efficiency
- temperature gets too high, stops components working
- requires fuse
Advantages
- Good to heat shit
What is electric power?
- Energy transferred per second
equations for energy produced in a circuit
E = I x V x t
power x time
E = Q x V
equations for power in a circuit
P = e/t
P = IV
P = I^2 * R
What is UK main’s supply?
50hz and 230V
