Flashcards
IV Characteristics
Cards in this deck (15)
- 1What is Ohm's law?Current in a conductor is proportional to the p.d across it, providing the temperature is kept constant (I ∝ V)
V = I x R - 2What is an Ohmic conductor?A material / conductor which obeys Ohm's law
- 3IV graph for an Ohmic material (e.g. resistor) :
- 4Why is the IV graph for a Ohmic material like this?Ohm's law is obeyed, so I ∝ V
Under constant physical conditions (e.g. temperature) - 5IV graph for filament lamp :
- 6Why is the IV graph for a filament lamp shaped like this?Ohm's law not obeyed
As V increases, I increases
As I increases, Temperature increases
As temperature increases, R increases
(therefore not straight line) - 7How would we find the resistance using an IV graph for an Ohmic conductor?Find gradient
(this works as we can rearrange V=IR to I=RV and say I=1/R x V. This is the same as y=mx+c as our intercept for I=1/R x V is 0, so I=1/R x V + 0 ) - 8How would we find the resistance using an IV graph for an filament lamp?Use values from the graph:
Vx/Ix = Rx - 9IV graph for diode (aka semi-conductor) :
- 10Why is the IV graph for a diode shaped like this?Non-Ohmic
If current is the wrong way (reverse bias) then resistance is really high so current is therefore tiny - 11What is forward bias?The direction current is able to flow
- 12What is threshold voltage and what is the value of threshold voltage for a diode?A minimum voltage needed to allow current to flow through and the value for a diode is 0.6V
- 13What kind of diodes have a higher threshold voltage than normal diodes?LED's
- 14What are the threshold voltages for : Diodes LED'sDiodes = 0.6 V
LED's = 1.5 V - 15On IV graphs, how do we get negative readings on the graph?Reverse the direction of the battery