I-V Characteristics Flashcards
I-V Graphs shows how […….] varies
Resistance
What is the circuit called that you use to investigate I-V characteristics of a component?
Test circuit
In a test circuit what do you use the variable resistor for?
To alter the Potential Difference and the current flowing through it
In a test circuit why do you repeat your measurements?
To take averages and to reduce the effect of random errors on your results
For the current through an ohmic conductor to be directly proportional to the Potential Difference what must remain constant?
The temperature
For an ohmic resistor what does a shallow gradient mean?
The conductor has a greater resistance
What is the I-V characteristic for a Filament Lamp?
The graph is curved
What happens to the curve of a filament lamp as Potential Difference rises?
The curve starts to get SHALLOWER (less steep gradient)
The resistivity of a metal increases with [………]
Temperature
How is charge carried through metals?
By free electrons in a lattice of positive ions
Explain how the resistivity of a metal increases with temperature.
- Charge is carried through metals by free electrons in a lattice of positive ions
- Heating up a metal makes the lattice ions vibrate more, meaning electrons collide with them more frequently, reducing their drift velocity and transferring some of their kinetic energy into other forms
- When they lose KE their speed and drift velocity decreases, so current decreases so it’s resistance increases
Where are semiconductors used?
Sensors
Why do semiconductors have a higher resistivity than metals?
Because there are fewer charge carriers available
What happens to a semiconductor if energy is supplied to the semiconductor? (Only occurs with some semiconductors)
More charge carriers are released so the current is increased and their resistance and resistivity decreases
What are three semiconductor components?
- Thermistors
- LDRs
- Diodes
