Resistance Flashcards
define resistance of component x
ratio between V and I. resists flow of charge
What is equation for resistance?
R = V/I
What is ohm’s law?
- There is a metalic conductor
- When temperature kept constant, the current is directly proportional to PD
- a = KV where k is a permanent constant and v is voltage
eg. if V doubled then A doubled
How does every component have resistance?
Each component, resists the flow of charge carriers through it.
What happens when temperature in the wire increases?
The positive ions in the wire have more internal energy and so vibrate more with greater amplitude. The frequency of collisions of the charge carriers and the positive ions increase, so charge carriers do more work, therefore they transfer more energy as they go through the wire. Increasing the resistance of the wire.
What is a charge carrier in a circuit.
Free electrons in the metal OR negative ions
How to calculate resistance in circuits with more than 1 resistor reading.
Sum of all resistor readings in a circuit.
How to calculate resistance in parallel circuits.
We do 1/R equals 1/r1 + 1/r2 etc
How to draw a current and volatage graph
Current is y axis and voltage is x axis.
What is small mA meaning
mili amps
What is equation for current and charge
Q equals IT
I equals Q/T
What are the graphs of current and voltage in:
1) resistors
2) bulb
3)led
Does the filament lamp behave the same way when polarities change?
Yes, regardless of polarity the filament lamp behaves the same way.
Remember: curve from negative to +
Does the LED behave same way regardless the polarity?
NO
Its a diode, it will not be same, it has no current when voltage negative.
Does resistor/ohmic conductor behave same when polarities change
Yes
